SELECT  METHODS. 


IN 


QUANTITATIVE  ANALYSIS 


BYRON  W.  CHEEVEB,  A.M.,   M.  D., 

Late  Acting  Professor  of  Metallurgy  in  the 
University  of  Michigan. 


Arranged  from  Prof.  Cheever's  manuscript  by 
FRANK  CLEMES  SMITH. 


PARTS    I   AND    II. 

SECOND  EDITION. 


ANN  ARBOR: 

REGISTER  PRINTING  AND  PUBLISHING  HOUSE. 
1888. 


COPYRIGHT,  1888, 

BY 
JENNIE  E.  CHEEVER. 


PAET  I. 
EKRATA. 


Pr  ge  8,  third  line,  weight  should  read  weigh. 

Page  33,  eleventh  line,  diliquescent  should  read  deliquescent;  Bottle 
12  should  read  Box  12. 

Page  35,  second  paragraph,  page  10  should  read  page  14. 

Page  39,  second  paragraph,  page  21  should  read  page  24. 

Page  49,  paragraph  (e),  page  20  should  read  page  28. 
v  Page  59,  fifth  paragraph,  page  (>o  should  read  page  66;  first  footnote 
should  read  Fresenius  439. 

Page  61.  first  paragraph,  page.  52  should  read  page  GO;  second  par- 
agraph, page  70  should  read  page  76. 

Page  63,  second  paragraph,  page  47  should  read  page  57. 


PAftT  I, 


LABOEATOEY  NOTES 


FOK  A 


BEGINNERS  COURSE 


QUANTITATIVE  ANALYSIS, 


Ceo?;  (f«ot> 

REFERENCES. 

ERESENIUS:  Quant.  Anal.;  7th  Ed, 

•CLASSEN. 

CBOOKES:  Select  Methods ;  2d  Ed. 

WATTS'  Dictionary. 

STJTTON:  Volumet.  Anal. ;  5th  Ed. 

HART:  Volumet.  Anal. 

Chemical  News. 


LIST   OF   ELEMENTS.* 
Hydrogen  =  1. 


Name. 

Symbol. 

Atomic 
Weight. 

Atomic 
Weight 
Adopted  in 
this  Edition. 

Aluminium  . 

Al 

21  04 

27  04 

Antimony. 

Sb 

119  6 

119  6 

Arsenic  .. 

As 

74  9 

75  0 

Barium    

Ba 

136  86 

136  9 

Bismuth  

Bi 

207  5 

207  5 

Bromine  

Br 

79  76 

79  8 

Boron  

B 

-  10.9 

11  0 

Cadmium  

Cd 

111  7 

111  7 

Calcium 

Ca 

39  91 

40  0 

Carbon. 

c 

11  97 

12  0 

Cerium  .  . 

Ce 

141  2 

141  2 

Chlorine  

Cl 

35  37 

35  37 

Chromium  

Cr 

52  45 

52  45 

Cobalt  ,  

Co 

58  6 

58  6 

Copper.  . 

Cu 

63  18 

63  18 

Fluorine  

F 

19  06 

19  06 

Gold  

Au 

196  2 

196  2 

Hydrogen  

H 

1 

1  0 

Iodine  

I 

J26  5 

126  5 

Iron  

Fe 

55  88 

56  0 

Lead  

Pb 

206  39 

206  4 

Lithium  

Li 

7  01 

7  01 

Magnesium    

Mg 

23  94 

24  0 

Manganese  

Mn 

54  8 

55  0 

Mercury  

Hg 

199  8 

199  8 

Molybdenum.. 

Mo 

95  9 

96  0 

Nickel  

Ni 

58  6 

58  6 

Nitrogen  

N 

14  01 

14  0 

Oxygen    . 

o 

15  96 

16  0 

Platinum.  .  .  . 

Pt 

194  3 

194  3 

Phosphorus   .  .  . 

p 

30  96 

31  0 

Potassium  

K 

39  03 

39  0 

Silver  

As 

107  66 

107  66 

Silicon  

sf 

28  0 

28  0 

Sodium  

Na 

22  99 

23  0 

Strontium  

Sr 

87  3 

87  3 

Sulphur.  . 

s 

31  98 

32  0 

Tin    

Sn 

117  35 

117  35 

Titanium.... 

Ti 

50  25 

50  25 

Tungsten  

W 

183  6 

183  6 

Uranium  

Ur 

239  8 

240  0 

Zinc  

Zn 

64  88 

65  0 

Meyer  Atomgewichte. 


819475 


RULES  FOR  WEIGHING. 

1.  Level  and  adjust  the  balance. 

2.  Always  place  the  substance  to  be  weighed  upon  the 
same  pan— most  conveniently  upon  the  left. 

3.  Never  place  the  substance  upon  the  naked  pan; 
use  counterpoised  watch-glasses,  or  a  weighed  porcelain 
or  platinum  dish.    (Never  use  paper). 

4.  Always  bring  the  balance  to  a  rest,  before  placing 
upon  or  removing  a  substance  or  weight  from  the  pans. 

5.  Use  forceps,  if  possible,  in  placing  upon  and  remov- 
ing dishes  from  the  pans. 

6.  Always  handle  weights  with  forceps;  never  touch 
them  with  the  hand. 

7.  Never  weigh  a  vessel  or  substance  while  warm. 

8.  Never  try  weights  at  random;  commence  with  the 
weight  nearest  to,  and  less  than  the  substance,  and  add 
the  weight  next  in  succession  till  the  correct  weight  is 
obtained. 

9.  Liquids,  and  solids  which  are  volatile,  or  give  off 
or  absorb  moisture  when  exposed  to  the  air,  must  be 
weighed  in  closed  vessels.    All  other  substances  may  be 
weighed  in  the  open  air. 


SPECIFIC  GRAVITY.* 

The  specific  gravity  of  a  body  is  the  weight  of  that 
body  as  compared  with  the  weight  of  an  equal  volume  of 
a  standard  body,  which  is  taken  as  unity.  In  all  cases  of 
solids  and  liquids,  this  standard  of  unity  is  pure  water 
at  60°  F.  =  15.5°  C. 

Water  being  taken  as  unity,  or  one,  any  other  sub- 
stance will  be  more  or  less  than  one.  The  results  are 
expressed  in  whole  numbers  and  decimals;  the  decimals 
are  carried  to  the  third  place. 

Water     =  1.000  (one,  not  one  thousand). 

Alcohol  =  0.815 

Sand        =  2.127 


Cfravimetric  Methods  of  Determining  the  Specific  Gravities 
of  Solids  and  Liquids. 

The  following  classification  will  serve  for  all  solids 
and  liquids  which  are  likely  to  occur  in  ordinary  investi- 
gations. 

1.  Liquids,  heavier  or  lighter  than  water. 

2.  Solids,  in  powder,  heavier  than  water  and  insoluble 
in  it. 

3.  Solids,  in  mass,  heavier  than  water  and  insoluble 
in  it. 

4.  Solids,  lighter  than  water  and  insoluble  in  it. 

5.  Solids,  soluble  in  water. 

CLASS  I.— Liquids,  heavier  or  lighter  than  water. 

Take  a  specific  gravity  bottle,  clean  and  dry  it;  cool 
and  weigh. 

*  Watts  Diet'  V— 357. 


8  SPECIFIC  GRAVITY. 

Now  fill  the  bottle  with  distilled  water  at  60°  F.,  (there 
must  not  be  any  air  bubbles  about  the  stopper)  and  again 
weight  it. 

It  will  not  be  accessary  to  repeat  these  weighings 
except  in  cases  of  accident. 

Empty  and  dry  bottle,  cool  and  fill  with  the  liquid  at 
60°  F.,  (avoiding  air  bubbles  as  before)  and  weigh. 

We  thus  obtain  the  weight  of  an  equal  volume  of  pure 
water  and  liquid  thus: 

Let  B  =  sp.  gr.  bottle,  W  =  distilled  water,  and  L  = 
the  liquid. 

B  +  W  =  30  grms.  B  +  L  =  38  grms. 
B  =  10  grms.  B  =  10  grms.     . 

W  =  20  grms.  L  -  28  grms. 

To  find  the  sp.  gr.  of  the  liquid,  divide  the  weight  of 
the  liquid  by  the  weight  of  pure  water. 

L        28 

—  =  —  =  1.400  sp.  gr.  of  the  liquid; 
W       20 
or,  placing  it  in  the  form  of  a  proportion, 

20  :  28  :  :  1.000  :  x,  =  sp.  gr. 

Determine  the  sp.  gr.  of  the  following  table  reagents : 
HC1— HN03-H(C2H302)-KHO-NH4HO— C2H6O. 

CLASS  II. — Solids,  in  powder,  heavier  than  water  and 
insoluble  in  it. 

(Soxes  1  and  2.) 

Clean  and  dry  the  specific  gravity  bottle,  cool  and  put 
into  it  from  2  to  5  grms.  of  the  powder  and  weigh.  Then 
fill  the  bottle  with  distilled  water  (avoiding  air  bubbles) 
and  weigh.  Result: 

B  +  W  =  30  grms.   B  +  S  =  20  grms. 

B  —  10  grms.    B  =10  grms. 


W  = 

20  grms.             S 

=  10  grms. 

B  +  S  + 

W  =  36grm. 

W    =  20 

B  +  S 

=  20     - 

W1  =  16. 

W1  =  16     "  W11  =    4. 


SPECIFIC  GRAVITY.  9 

W  =  the  weight  of  water  which  the  bottle  holds. 
W1  =    "         "  "      above  the  substance. 

•\yn—    K         c<  «      displaced  by  the  substance. 

Displaced  water  has  the  same  volume  as  the  substance 
which  displaced  it;  and  since  we  have  the  weight  of  the 
substance,  and  the  weight  of  the  water  displaced  by  it, 
we  therefore  have  the  weight  of  an  equal  volume  of  both. 

Applying  the  rule  just  given,  we  have 

S        10 

—  =  —  =  2.500  the  sp.  gr.  of  S. 
W11      4 

CLASS  III.— Solids,  in  mass,  heavier  than  water  and 
insoluble  in  it. 

(Sox  5.) 

Suspend  the  substance  from  the  arm  of  the  balance  by 
means  of  a  horse-hair,  and  then  weigh.  Now  place  a 
beaker  of  distilled  water  in  such  a  position  that  the  sub- 
stance hangs  freely  in  it,  and  again  weigh,  (see  that  no 
air  bubbles  adhere  to  the  substance). 

The  loss  in  weight  is  equal  to  that  of  the  water  dis- 
placed. Thus 

S  in  air        =  25  grms. 
"      water  =  15     " 


Loss      =  10     " 
which  is  the  weight  of  the  displaced  water,  =  W 

S        25 

—  =  —  =  2.500  sp.  gr.  of  S. 
W        10 

CLASS  IY. — Solids  lighter  than  water  and  insoluble 
in  it. 

(Soxes  4  and  5.) 

These  being  lighter  than  water,  will  not  sink  in  it;: 
therefore  some  heavy  substance  must  be  attached  to  them,, 
to  sink  them,  and  thus  displace  the  water. 


10  SPECIFIC  GRAVITY. 

Take  as  an  example,  wood: 

1.  Weight  of  sinker          in  air  =    50. 

2.  "         "      "  +  wood    "       =  183. 

wood    "       =  133. 

3.  Weight  of  sinker  +  wood  in  water  =  38. 

4.  "        "       "      in  water  =  44. 

2wt.—   3wt.       (  Weight  of  the  water  displaced  )      Wi 
183  —  38  =  145  (     by  sinker  and  wood.  J 

Iwt.—  4wt.       (  Weight  of  the  water  displaced  )  _  W11 
50—44=     6}     by  sinker.  J  ~ 

W1  —  W11          (  Weight  of  the  water  displaced  )  _  W111 
145  —   6  =  139  I     by  wood.  J  ~ 

Wood      133 

=  —  =  0.956  sp.  gr.  of  wood. 

Wm        139 


CLASS  V.— Solids  soluble  in  water. 
(Sox  6.*) 

Select  some  liquid  in  which  the  solid  is  insoluble,  and 
-determine  its  sp.  gr. 

Then  proceed  to  determine  the  sp.  gr.  of  the  solid 
according  to  directions  given  for  Class  Two,  using  this 
liquid  instead  of  water. 

(The  substance  in  Box  6  is  insoluble  in  alcohol.) 

Multiply  the  sp.  gr.  thus  obtained  by  the  sp.  gr.  of  the 
iliquid  used;  the  product  will  be  the  true  sp.  gr. 


QUANTITATIVE  ANALYSIS. 

PRELIMINARY  STEPS. 

1.  Selecting  the  Sample.— The  mode  of  selecting  the 
sample  will  depend  upon  the  object  sought.  In  commer- 
cial work  the  sample  should  be  so  selected  as  to  represent 
as  nearly  as  possible  the  average  quality  of  the  whole. 
This,  can  be  best  accomplished  by  pulverizing  a  large 
quantity,  taken  from  different  parts  of  the  mass,  thor- 
oughly mixing  the  same  and  then  taking  from  this  a 
small  sample  for  analysis. 

In  technical  work,  pure,  clean  crystals  should  be  se- 
lected. 

2.  Mechanical  Division.— Substances  soluble  in  water 
or  readily  soluble  in  acids,  are  only  pulverized  moderately 
fine;  they  must  be  fine  enough,  however,  to  insure  a 
uniform  sample.    A  porcelain  mortar  answers  for  this 
work.    Substances  not  readily  dissolved  by  acids,  or  sol- 
uble only  after  fusion,  must  be  reduced  to  an  impalpable 
powder  with  an  agate  mortar. 

3.  Drying  the  Sample. — The  sample,  when  ready  for 
analysis,  must  be  in  a  definite  state,  that  is,  in  a  condition 
in  which  it  can  always  be  obtained  a  second  time,  if  by 
accident  or  otherwise  a  new  sample  has  to  be  prepared. 
This  is  accomplished  by  drying,  which  removes  the  hy- 
groscopic moisture.    The  mode  of  drying  will  depend 
upon  certain  physical  characteristics  peculiar  to  different 
bodies. 

Classification  of  Substances,  with  reference  to  the  mode 
of  drying. 

(a).  Substances  which  lose  water  of  constitution  or 
•crystallization  when  exposed  to  air  are  dried  by  pressing 
between  folds  of  blotting  paper. 


12  QUANTITATIVE  ANALYSIS. 

(6).  Substances  which  only  give  off  water  in  artifici- 
ally dried  air,  are  pressed  between  folds  of  blotting  paper 
and  then  left  for  some  time  exposed  to  the  air,  protected 
from  dust  by  paper  or  otherwise. 

(c).  Substances  which  undergone  change  in  dry  air, 
but  lose  water  at  100°  C.,  are  dried  in  a  desiccator  over 
H2SO4  or  CaCl2. 

(d).  Substances  which  give  off  all  their  moisture  at 
100°  C.,  but  undergo  no  other  change,  are  dried  in  a  water 
bath  at  100°  C. 

(e).  Some  substances  retain  moisture  at  100°  C.,  this 
moisture  is  generally  determined  and  returned  as  per  cent. 


GRAVIMETRIC  DETERMINATIONS. 

The  crucible  which  is  used  for  igniting  and  weighing 
the  precipitate  must  be  cleaned,  heated,  cooled  in  the 
desiccator,  and  weighed  before  each  ignition. 

The  ash  of  the  filter  must  also  be  determined  by  in- 
cinerating two  or  more  filters  till  white,  and  weighing 
the  resulting  ash. 

Boxl. 

BARIUM  CHLORIDE. 

Estimation  of  Barium. — Take  an  exact  weight  (about 
0.5  grm.*)  of  the  substance,  dissolve  in  100  c.  c.  of  water, 
acidulate  with  HC1,  boil  and  add,  drop  by  drop,  dilute 
H2S04  as  long  as  a  precipitate  forms;  boil  for  some  time, 
then  place  to  one  side  until  the  precipitate  has  completely 
subsided ;  filter  by  decantation  and  wash  with  hot  water, 
until  silver  nitrate  produces  no  turbidity  in  the  washings. 

Dry,  ignite,  cool,  add  a  few  drops  of  HjSO^,  ignite 
moderately  till  fumes  are  no  longer  given  off,  cool  and 
weigh. 

Result,  BaSO4. 

Calculation. 

BaSO4  :  Ba  :  :  wt  BaSO4  :  x  =  wt.  of  Ba  found. 
Wt.  taken  :  x  :  :  100  :  y  —  per  cent,  of  Ba. 

Estimation  of  Chlorine.— Dissolve  0.2  grms.  in  50  c.  c. 
of  warm  water,  add  silver  nitrate  in  slight  excess,  then 
acidify  with  HNO3,  heat  and  agitate  briskly;  place  the 
beaker  for  a  short  time  in  a  warm,  dark  place,  then  filter 


*The  beginner  should  never  weigh  1.  grm.  or  .5  grm.,  but  take  a 
quantity,  near  the  amount  specified,  and  weigh  it  carefully.  Some- 
times a  definite  amount  will  be  specified,  when  from  the  context  it 
will  be  evident  that  an  approximate  quantity  is  intended. 


14       GBAVIMETEIC  DETEEMINATIONS. 

and  wash  with  hot  water.    Wash  till  filtrate  gives  no 
precipitate  on  adding  HC1. 

Dry,  remove  the  precipitate  from  the  filter,  incinerate 
the  filter,  then  add  the  precipitate  to  the  ash,  cool,  add  5 
drops  of  HNO3,  heat  gently,  then  add  10  drops  HC1,  heat 
on  water  bath  till  dry,  then  ignite  until  the  AgCl  begins 

to  fuse. 

Kesult  =  AgCl. 

Calculation. 

AgCl  :  Cl  :  :  wt.  AgCl  :  x  =  Cl  in  wt.  taken. 
Wt.  taken  :  x  :  :  100  :  y  =  per  cent,  of  Cl. 
To  remove  the  fused  AgCl  from  the  crucible,  place 
upon  it  a  piece  of  Zn  and  add  dilute  H2SO4. 

Sox  2. 

MAGNESIUM  SULPHATE. 

Estimation  of  Magnesium  Oxide— Dissolve  0.5  grm.  in 
50  c.  c.  of  water,  add  NH^Cl,  then  NH^OH  in  excess  (no 
precipitate  should  be  formed;  if  there  is,  add  HC1  till 
dissolved;  then  add  NH4OH  in  excess);  cool,  and  add 
sodium-ammonium  phosphate  in  slight  excess;  agitate 
briskly,  allow  to  stand  till  the  supernatant  liquid  is  clear; 
filter  and  wash  the  precipitate  with  a  mixture  of  one 
part  ammonium  hydrate  and  three  parts  water,  until  the 
addition  of  HKO3  and  AgK03  to  the  filtrate  does  not 
produce  a  precipitate.  Dry  and  ignite  (commencing  with 
a  low  heat)  until  constant  weight  is  obtained. 

If,  after  ignition,  the  precipitate  is  not  pure  white, 
moisten  it  with  nitric  acid,  and  again  ignite. 

Result  =  Mg2P2O7. 

Calculation. 

Mg,P2O7  :  2MgO  :  :  wt.  Mg2P2O7  :  x  =  MgO  in  wt.  taken. 
Wt.  taken  :  x  :  :  100  :  y  =  per  cent,  of  MgO. 

Estimation  of  Sulphuric  Add.— Dissolve  0.5  grm.  in 
30  c.  c.  of  water,  acidulate  with  HC1,  boil  and  add  to  it  a 


GRAVIMETRIC  DETERMINATIONS.  15 

boiling  solution  of  Barium  chloride,  as  long  as  a  precip- 
itate is  formed;  (now  proceed  as  directed  under  Box  1 
for  the  estimation  of  Barium.) 

Box  3. 

FERROUS  SULPHATE. 

Estimation  of  Metallic  Iron.— Dissolve  1  grm.  in  25 
c.  c.  of  water  strongly  acidulated  with  HC1,  boil,  and  add 
small  crystals  of  KC1O3,  until  all  the  iron  is  oxidized  to 
the  ferric  salt;  continue  the  boiling  and  add  more  HC1  if 
necessary,  until  the  KC1O3  is  decomposed  and  the  solution 
no  longer  emits  an  odor  of  chlorine;  cool  and  add  NH4OH 
in  excess;  boil,  filter  by  decantation  and  wash  with  hot 
water,  until  silver  nitrate  produces  no  turbidity  in  the 
washings  when  acidulated  with  HNO3. 

Dry,  ignite  and  weigh. 

Result  =  Fe2O3. 

Calculation. 

Fe203  :  2Fe  :  :  wt.  Fe2O3  :  x  —  Fe  in  wt.  taken. 
Wt.  taken  :  x  :  :  100  :  y  =  per  cent,  of  Fe. 

Sox  4. 

CALCIUM  CARBONATE. 

Estimation  of  Calcium  Oxide— Take,  0.5  grm.,  place 
in  a  large  beaker,  add  30  c.  c.  of  water,  cover  with  a  clock- 
glass,  then  add  gradually  HC1,  till  effervescence  ceases* 
heat,  add  ammonium  oxalate  in  moderate  excess,  and 
then  ammonia  in  slight  excess,  boil,  remove  to  a  warmr> 
place,  and  let  stand  twelve  hours;  filter  by  decantation 
and  wash  with  hot  water,  until  the  wash  water,  acidu- 
lated with  nitric  acid,  gives  no  precipitate  with  silver 
nitrate. 

Dry,  ignite  at  a  moderate  heat,  cool,  moisten  with* 
ammonium  carbonate,  heat  to  faint  redness,  cool  and 
weigh;  repeat  this  operation  until  constant  weight  is- 
obtained. 

Result  -  CaCO3. 


16  GRAVIMETRIC  DETERMINATIONS. 

Calculation. 

CaCO3  :  CaO  :  :  wt.  CaCO3  :  x  =  CaO  in  wt.  taken. 
Wt.  taken  :  x  :  :  100  :  y  =  per  cent,  of  CaO. 

Estimation  of  Carbon  Dioxide. — When  CO2  is  com- 
bined with  a  base,  it  is  generally  determined  by  loss  of 
weight  which  the  substance  sustains,  when  treated  with 
a  stronger  acid  or  acid  compound.  The  more  common 
method  is  to  employ  some  simple  apparatus  which  will 
permit  the  expulsion  of  the  CO2,  without  loss  from  other 
causes.  The  apparatus  is  charged  with  a  weighed  quan- 
tity of  the  substance  containing  the  CO2,  and  with  the 
acid  which  is  to  expel  it,  it  is  then  weighed,  and  after 
weighing,  the  acid  is  allowed  to  come  in  contact  with  the 
substance,  when  the  CO2  is  expelled,  the  apparatus  is 
weighed  again;  the  loss  in  weight  is  the  weight  of  C02. 

Wt.  taken  :  loss  :  :  100  :  x  =  per  cent,  of  C02. 
Sox  5. 

SODIUM   PHOSPHATE. 

Estimation  of  Phosphoric  Acid.— Dissolve  0.5  grm.  in 
50  c.  c.  of  water,  add  NH4OH  in  excess,  cool,  then  add 
magnesia  mixture  in  excess,  agitate  briskly;  after  stand- 
ing three  hours  in  a  cool  place,  filter,  and  wash  with  a 
mixture  of  one  part  NH4OH,  and  three  parts  water, 
until  the  wash  water  acidulated  with  HNO3,  gives  no 
precipitate  with  AgNO3. 

(The  precipitate  is  slightly  soluble  in  dilute  ammonia 
water). 

Dry,  and  ignite.    (For  precautions  see  Box  2). 

Eesult  =  Kg,  P2  OT. 

Calculation. 

.Mg2P2O7  :  P2O5  :  :  wt.  Mg2P2O7  :  x  =  P2O5  in  wt.  taken. 
Wt.  taken  :  x  :  :  100  :  y  =  per  cent,  of  P2O5. 


GRAVIMETRIC  DETERMINATIONS.  17 

Sox  6. 
AHSENIOUS   ANHYDRIDE. 

Estimation  of  Arsenic.— Dissolve  0.5  grm.  in  KHO, 
with  the  aid  of  heat;  acidulate  with  HC1,  maintain  the 
heat  at  70°  C.,  and  pass  H2S  gas  through  the  solution  for 
one  hour,  filter  and  wash  with  hot  water.  If  As2  S3  ad- 
heres to  the  tube  and  beaker,  dissolve  it  in  NH4OH  and 
reprecipitate  with  dilute  HC1,  and  transfer  it  to  the  filter. 
Dissolve  the  moist  precipitate  on  the  filter  with  cold 
NH4OH,  to  this  ammoniacal  solution  add  cold  dilute  HC1 
until  the  solution  is  moderately  acid,  filter  through  coun- 
terpoised filters,  and  wash  with  water.  Dry  at  100°  C., 
cool  and  weigh. 

Eesult  =  As2S3. 

Calculation. 

As2S3  :  As2  :  :  wt.  As2S3  :  x  =  As  in  wt.  taken. 
Wt.  taken  :  x  :  :  100  :  y  —  per  cent,  of  As. 


VOLUMETRIC  ANALYSIS. 

Volumetric  analysis  is  a  method  for  determining 
quantity  by  measure.  The  reagent  and  the  material 
under  examination  must  therefore  be  in  solution. 

The  reagents  which  must  have  an  exact  and  known 
strength  are  called  Standard  Solutions. 

These  are  divided  into    1.  EMPIRICAL.    2.  NORMAL. 

Empirical  Solutions,  are  used  for  estimating  one  ele- 
ment only.  They  are  prepared  without  reference  to  the 
atomic  weights,  and  are  generally  of  such  strength,  that 
1  c.  c.  =  1  per  cent,  or  the  fraction  of  a  per  cent,  when 
titrating  a  given  weight  of  the  unknown. 

Normal  Solutions,  are  used  for  estimating  all  elements, 
with  which  they  produce  a  distinct  reaction.  They  are 
prepared  so  that  a  given  measure  contains  an  exact 
atomic  weight. 

Normal  Solutions,  are  prepared  so  that  one  litre  at  16° 
C,  shall  contain  the  hydrogen  equivalent  of  the  active  re- 
agent weighed  in  grms.  (H  =  1).  If  the  substance  is 
univalent  the  full  atomic  weight  is  used,  if  bivalent  one- 
half,  and  if  trivalent  one-third.  This  rule  does  not  hold 
good  in  all  cases,  and  the  whole,  or,  an  aliquot  part  of 
the  atomic  weight  of  the  reagent  must  be  taken,  depend- 
ing upon  its  peculiar  reaction  in  any  given  analysis. 

Solutions  of  less  strength  than  the  normal  will  often 
be  required.  These  solutions  may  be  shortly  designated 
as  N"  normal;  f  seminormal;  f  quintinormal;  ^  decinor- 
mal;  T$T  centinormal. 

Titrate,  is  the  term  applied  to  the  method  of  estimat- 
ing quantitatively  the  amount  of  pure  substance  con- 
tained in  a  given  substance  or  solution,  by  a  standard  or 
titrated  solution. 

End  reaction,  is  the  term  applied  to^that  point  in  the 


VOLUMETBIC  ANALYSIS.  19 

operation  where  no  further  change  takes  place  between 
the  known  and  the  unknown.-  The  end  reaction  must  be 
manifest  to  the  eye,  either  by  some  change  in  the  solution 
itself,  or  by  an  indicator.  Keagents  which  produce  no 
visible  change,  cannot  be  used  to  prepare  standard  solu- 
tions. 

Normal  factor,  is  used  to  express  the  amount  in  grms 
of  the  active  reagent  in  1  c.  c.  of  a  normal  solution. 

CLASSIFICATION  OF  METHODS. 

(1).  Analysis  by  saturation,  or  acidimetry  and  alka- 
limetry. 

(2).    Analysis  by  oxidation  and  reduction. 
(3).    Analysis  by  precipitation. 

Alkalimetry  and  Acidimetry — or  the  methods  for  esti- 
mating the  per  cent,  of  actual  alkali  or  acid  in  a  given 
solid  or  solution. 

The  end  reaction  in  these  determinations  is  not  mani- 
fested by  the  solution  itself,  hence  an  indicator  must  be 
used. 

INDICATORS. 

Phenolphthalein — is  a  yellowish  powder,  soluble  in 
alcohol.  To  prepare  a  solution  for  use  dissolve  .010  grm. 
in  10  c.  c.  of  50  per  cent,  alcohol.  One  or  two  drops  is 
sufficient  for  each  titration.  Acids  produce  no  change  in 
color,  alkalies  produce  an  intense  purple-red. 

This,  though  perhaps  not  the  best  indicator,  has  been 
found  to  work  well  in  the  hands  of  beginners,  on  account 
of  its  great  sensitiveness. 

It  cannot  be  used  for  titrating  ammonia,  or  the  caus- 
tic alkalies  when  ammoniacal  salts  are  present.  Cold  or 
only  moderately  warm  solutions  must  be  used  in  titrat- 
ing, oxalic,  citric,  tartaric,  acetic  and  other  organic  acids, 
with  potassium  or  sodium  hydrate.  Hot  solutions  must 
be  used  in  titrating  alkaline  and  earthy  hydrates,  carbo- 
nates, and  bicarbonates,  and  sulphides,  with  mineral  acids. 


20  VOLUMETRIC  ANALYSIS. 

STANDARD  SOLUTIONS. 

In  preparing  standard  solutions,  it  is  not  always  pos- 
sible to  obtain  the  reagent  in  a  definite  and  permanent 
form,  so  that  the  exact  amount  required  can  be  weighed 
or  measured  out.  In  such  cases  the  standard  is  obtained 
by  titrating  the  reagent  with  some  standard  solution, 
and  then  calculating  the  dilution  required  to  bring  the 
reagent  to  the  standard.  The  volumes  of  all  standard 
solutions  of  a  given  class  (as  ^)  must  be  equal,  that  is 
1  c.  c.  of  a  given  ^  solution  must  exactly  neutralize  1  c.  c. 
of  an  ^  solution  of  the  opposite  kind. 

In  preparing  ^  solutions  for  this  part  of  the  work,  we 
will  commence  with  oxalic  add,  since  this  acid  can  be 
obtained  in  a  definite  and  permanent  form. 

^  OXALIC  ACID. 
C2O4H2,  2H2O  =  126  -=-  2  =  63.    6.3  grms.  per  litre. 

Weigh  out  exactly  6.3  grms  of  the  freshly  prepared 
crystals  of  oxalic  acid,  dissolve  in  water,  and  dilute  to 
one  litre. 

Each  c.  c.  contains  .0063  grms  of  the  acid;  therefore 
.0063  is  the  decinormal  factor  of  oxalic  acid. 

^y  POTASSIUM  HYDRATE. 

KHO  =  56.    5.6  grms.  per  litre. 

Take  50  c.  c.  of  the  table  reagent,  and  dilute  with 
water  to  600  c.  c.,  cool,  and  titrate  with  f\  oxalic  acid,  as 
follows:  Take  5  c.  c.  of  the  KHO  solution,  add  2  drops  of 
the  indicator,  and  run  in  gradually  from  a  burette  ^  ox- 
alic acid,  until  a  drop  just  disperses  the  red  color.  Make 
at  least  six  titrations  and  take  the  average  result. 

Example  for  Calculating  the  Dilution. — Suppose  5  c.c. 
of  the  KHO  solution  required  8  c.  c.  of  the  ^  oxalic  acid 
to  produce  the  end  reaction,  or  to  neutralize  it.  The  pot- 
ash solution  is  therefore  the  stronger  and  must  be  diluted 
with  water,  so  that  5  c.  c.  of  it  will  require  just  5  c.  c.  of 
the  T%  oxalic  acid  to  neutralize  it;  when  so  diluted,  it  will 


VOLUMETRIC  ANALYSIS. 

be  an  ^  solution,  for,  as  we  have  said,  ^  solutions  are  all 
equal,  and  1  c.  c.  of  any  ^  solution  can  be  substituted  for 
1  c.  c.  of  any  other  ^  solution  of  the  same  nature. 

The  graduated  cylinder  has  left  in  it  550  c.  c.  of  the 
KHO  solution;  how  many  c.  c.  of  an  T^  solution  will  it 
make? 

5  c.  c.  :  8  c.  c.  :  550  c.  c.  :  x  =  880  c.  c. 

Now  add  water  to  the  550  c.  c.  until  it  has  been  raised 
to  880  c.  c.,  mix  thoroughly,  and  again  titrate  with  the  T\ 
oxalic  acid;  the  solutions  should  be  equal. 

Each  c.  c.  contains  .0056  grms  KHO. 

Burettes  with  glass  taps  must  not  be  used  for  measur- 
ing caustics. 

^  SULPHURIC  ACID. 

H2SO4  =  98  -r-  2  =  49.    4.9  grms  per  litre. 

Take  5  c.  c.  of  the  table  reagent,  dilute  with  300  c.  c.  of 
water  in  a  porcelain  dish,  transfer  to  the  graduated  cylin- 
der, cool,  and  titrate  with  &  KHO  solution;  see  direc- 
tions for  titrating  and  making  an  -f^  solution  of  KHO. 

Each  c.  c.  contains  .0049  grms.  H2S04. 

^  NITRIC  ACID. 

HNO3  =  63.    6.3  grms.  per  litre. 

Take  about  5  c.  c.  of  the  table  reagent,  dilute  with  200 
c.  c.  of  water,  and  titrate  with  &  KHO  solution;  see 
direction  for  H2SO4. 

Each  c.  c.  contains' .0063  grms.  HNO3. 

(The  H]STO3  must  be  free  from  nitrous  fumes). 

NORMAL  OXALIC  ACID. 

Take  6.3  grms.,  dissolve  in  80  c.  c.  of  water,  and  dilute 
to  100  c.  c. 

NORMAL   SODIUM  HYDRATE. 

Take  about  15  grms.  NaHO,  place  it  in  a  porcelain 
dish,  dissolve  in  150  c.  c.  of  water,  cool,  transfer  to  a  grad- 
uated cylinder,  and  titrate  with  normal  oxalic  acid. 


22  VOLUMETRIC  ANALYSIS. 

From  the  results  calculate  the  dilution  necessary  to  make 
a  normal  solution. 

NORMAL  TARTARIC  ACID. 

Take  about  20  grms.  tartaric  acid,  dissolve  in  150  c.  c. 
of  water,  cool,  and  titrate  with  normal  sodium  hydrate. 

Titrations. 

All  material,  whether  solid  or  liquid,  which  is  to  be 
titrated  for  the  per  cent,  of  any  given  element,  must  be 
weighed. 

For  convenience  in  weighing,  dissolving,  or  diluting, 
select  a  two-ounce,  globe-shaped  flask,  clean,  and  dry,  and 
then  graduate  by  running  into  it,  water,  from  a  burette 
till  a  distinct  meniscus  is  formed  in  the  neck,  and  an  even 
number  of  c.  c.  has  been  used;  mark  this  point  by  a  label 
which  bears  the  number  of  c.  c,  used. 

This  we  will  call  the  weighing  flask. 

TITRATION  OF  HYDROCHLORIC  ACID. 

HC1  =  36.37.    ft  factor  =  .003637. 

Take  about  5  c.  c.  o£  the  table  reagent,  place  it  in  the 
weighing  flask,  and  weigh;  dilute  with  water. 

Mix  thoroughly,  cool,  and  dilute  to  the  mark.  Fill  a 
glass  tap  burette  with  this  solution,  and  a  Mohr's  burette 
with  ft  KHO. 

Run  into  a  small  beaker  5  c.  c.  of  the  HC1  solution,  add 
two  drops  of  the  indicator  and  titrate  with  the  ft  KHO; 
repeat  the  titration  three  or  four  times  and  take  the  aver- 
age result. 

Calculation. 

To  find  the  per  cent,  of  HC1. 

HC1  taken,  weighed  5.6  grms.  Weighing-flask  holds  60  c.  c. 
20  c.  c.  of  ^0  KHO  were  required  to  neutralize  5  c.  c.  of  the 

diluted  HC1. 
5  c.  c  HC1  :  20  c.  c.  ft  KHO  :  :  60  c.  c.  :  x  =  240  c.  c.  ft 

KHO. 
Therefore  240  c.  c.  ft  KHO  would  be  required  to  neu- 


VOLUMETBIC  ANALYSIS.  23 

tralize  5.6  grms.  HC1  (that  is  the  60  c.  c.);  or  by  diluting 
the  60  c.  c.  with  water  to  240  c.  c.  we  would  have  an  ft 
solution  of  HC1. 

1  c.  c,  of  an  -ft  HOI  contains  .003637  grms.  HC1,  there- 
fore, 1  :  .003637  : :  240  :  y  =  0.87288  grms.  HC1  in  wt.  taken. 

Wt.  taken  (5.6  grms.)  :  0.87288  :  :  100  :  z  -  per  cent, 
of  HC1  =  15.58. 

Volatile  liquids,  as  NH4OH  and  HC#  must  be  weighed 
in  well  stopped  bottles. 

The  titration  of  Acetic  Acid  by  a  standard  caustic 
alkali  is  not  rigidly  exact,  for  neutral  acetates  have  an 
alkaline  reaction. 

Titrate  the  following  table  reagents  : 

H]STOS  ft  factor  =  .0063 

HC1  "       "      =  .003637 

CaO,H4  "        "      =  .006 

KHO  "        "      =  .0056 

Boxl. 

CITRIC  ACID.    C6O7H8  +  H2O  =  210  -f-  3  =  70. 
ft  factor  =  .007 

Dissolve  about  0.2  grm.  in  water,  in  the  weighing 
ilask,  and  dilute  to  the  mark,  then  titrate  with  ft  KHO. 

Sox  2. 

SODIUM  CARBONATE.     Na2  CO3. 

To  be  titrated  for  Na2O  =  62  -=-  2  =  31. 
ft  factor  of  Na20  =  .0031. 

Place  about  0.5  grm.  in  the  weighing  flask,  dissolve  in 
water  and  dilute  to  the  mark. 

Take  5  c.  c.  of  this  solution  in  a  small  beaker,  add  some 
water,  then  add  two  drops  of  the  indicator,  and  run  in 
from  a  burette  ft  H2SO4,  %  c.  c.  at  a  time  (boiling  after 
each  addition)  till  the  H2SO4  is  in  excess;  boil  at  least  five 
minutes  after  the  last  addition  of  HZSO4.  How  titrate 
back  the  excess  of  H8S04  with  ft  KHO.  A  drop  or  two 


24  VOLUMET1UC  ANALYSIS. 

of  the  indicator  may  be  required  from  time  to  time  dur- 
ing the  titration. 

The  difference  between  the  HgSO^  and  KHO  used,  is 
the  amount  of  H2!SO4  required  to  neutralize  the  5  c.  c. 

Box  3. 

SODIUM  BICARBONATE.     NaHCO3. 

To  be  titrated  for  NaHO  =  40 

ft  factor  of  NaHO  =•  .004 
Follow  directions  for  Box  2. 

Sox  4. 

CALCIUM  CARBONATE.     CaCO3. 

To  be  titrated  for  CO8  =  44  -5-  2  =  22. 

Normal  factor  for  CO2  =  0.022 

Take  about  .05  grm.  in  a  large  beaker,  add  water 
enough  to  cover  the  bottom  of  the  beaker,  then  titrate 
according  to  directions  given  for  Box  2,  using  normal 
HNO3  in  place  of  ft  H8S04. 

Bottle  5. 

SOLUTION  OF  CAUSTIC  POTASH  AND  SODA. 

(Must  not  be  weaker  than  a  normal  solution). 

Normal  factor  of   KHO  =  .056. 

Normal  factor  of  NaFO  =  .04. 

Place  about  10  grms.  mafias)  (must  not  dilute),  run 
in  from  a  burette  normal  tarta  ;  acid,  till  neutral  or 
faintly  acid,  note  the  number  of  ,  c.  used,  and  then  run 
in  just  as  much  more.  This  will  >rm  a  bitartrate  of  pot- 
ash and  soda;  cork  the  flask  and  aake  violently  for  a  few 
minutes,  this  will  cause  the  p'  assium  bitartrate  to  sep- 
arate almost  completely,  sine  it  is  insoluble  in  sodium 
bitartrate.  Filter  and  wher  the  nitrate  has  all  passed 
through,  rinse  out  the  flask  with  5  c.  c.  of  water  and  pour 
it  on  the  filter;  when  all  has  passed  through,  titrate  the 
filtrate  with  normal  NaHO;  the  number  of  c.  c.  of  normal 
NaHO  required,  equals  the  soda  in  the  mixture. 


VOLUMETRIC  ANALYSIS.  25 

Calculation. 

10  grms.  of  the  solution  were  taken.  5  c.  c.  of  normal 
NallO  were  used;  5  X  .04  =  0.2  grms.  of  NaHO  in  wt. 
taken. 

10  :  0.2  :  :  100  :  x  =  2  per  cent,  of  NaHO. 

24  c.  c.  of  normal  tartaric  acid  were  used;  24  c.  c. — 10 
c.  c.  (the  amount  of  tartaric  acid  in  combination  with 
soda  as  bitartrate)  =  14  c.  c.  the  amount  of  acid  in  com- 
bination with  the  potash  as  bitartrate;  14  c.  c.  -+-  2  = 
7  c.  c.,  the  amount  of  normal  acid  required  to  make  a  neu- 
tral tartrate  of  the  potash. 

7  x  .056  =  .392  grm.  KHO  in  wt.  taken. 
10  :  .392  :  :  100  :  y  =  3,92  per  cent,  of  KHO. 


OXIDATION  AND  REDUCTION. 

The  most  available  oxidizing  reagents  are 

KMnO4,   K2Cr2O,,  and  I. 
The  most  available  reducing  reagents  are 
FeSO4,  C3O4H22H2O,  H2SO3,  Na2S2O3,  As2O3,  and  SnCl2. 

&  POTASSIUM  PERMANGANATE. 

KMnO4  =  158  -f-  5  =  31.6.    3.16  grms.  per  litre. 

Select  some  clean  crystals,  dry  them  for  forty-eight 
hours  in  a  desiccator  over  H2SO4;  then  weigh  out  3.16 
grms.,  dissolve  in  water  and  dilute  to  one  litre.  If  the 
salt  is  pure,  the  solution  will  be  •&;  but  as  this  is  not 
always  the  case  it  must  be  titrated  with  some  reducing 
reagent  which  has  a  definite  and  constant  composition. 
&  KMnO4  cannot  be  used  when  there  is  much  free  HC1 
present  in  the  solution  to  be  titrated,  for  free  HC1  reduces 
the  permanganate. 

In  preparing  standard  solutions  it  is  never  safe  to  rely 
upon  a  solution  ma.cle  by  taking  a  required  weight,  for 


2b  VOLUMETRIC  ANALYSIS. 

there  may  be  some  impurity  in  the  reagent.  The  solution 
should  always  be  compared  with  one  or  more  solutions  of 
the  opposite  kind. 

TITRATION  OF  PERMANGANATE. 

(a)  With  ft  Ferrous  Sulphate— Measure  with  a  pipet- 
te, 5  c.  c.  of  ft  FeSO4  into  a  small  beaker,  add  some  dilute 
H2SO4  (1  to  5),  and  titrate  with  the  ft  permanganate,  till 
a  faint,  permanent  permanganate  color  is  produced,  (use 
a  glass  tap  burette). 

Reaction. 

10FeSO4  +  8II2SO4  +  2KMnO4  =  5Fe2(SO4)3  + 
2MnSO4  +  K2SO4  +  8H2O. 

(6)  With  ft  Oxalic  Acid. — Follow  directions  given 
under  (a);  (warm  the  oxalic  acid  to  60°  C.,  before  titrating). 

Reaction. 

5C2H204  +  3H2S04  -f  2KMn04  =  K2SO4  +  2MnSO4 
+  8H20  +  10C02. 

(c)  With  ft  Sodium  Hyposulphite. — Measure  into  a 
flask  one  ounce  of  KI— table  reagent— (which  has  no  free 
iodine),  add  2  c.  c.  HC1  (1.16),  dilute  largely  with  water, 
then  run  in  5  c.  c.,  of  ft  KMnO4,  cork  the  flask,  and 
shake  thoroughly;  (must  be  kept  cold),  now  titrate  with 
ft  sodium  hyposulphite,  until  the  solution  is  colorless, 
then  run  in  ft  KMnO4,  one  drop  at  a  time  till  the  iodine 
color  re-appears. 

ft  POTASSIUM  BICHROMATE. 

K2Cr2O7  =  294.9  -j-  6  =  49.15.    4.915  grms.  per  litre. 

Weigh  4.915  grms.  of  the  pure  crystals,  dissolve  in 
water,  and  dilute  to  one  litre. 

Bichromate  possesses  the  advantage  over  permangan- 
ate, that  it  is  absolutely  permanent  in  solution,  may  easily 
be  obtained  in  a  pure  state,  may  be  used  in  a  Mohr's 
burette,  and  can  be  used  in  the  presence  of  free  sulphuric 
or  hydrochloric  acid.  It  possesses  the  disadvantage,  in 


VOLUMETRIC  ANALYSIS.  27 

that,  it  requires  an  indicator,  and  cannot  be  used  in  the 
presence  of  zinc. 

Indicator  Required. 

Potassium  Ferricyanide—must  be  freshly  prepared, 
and  so  dilute,  that  when  a  drop  is  placed  on  a  marble  slab 
it  shows  but  a  faint  color. 

TITRATION  OF  BICHROMATE. 

(a)  With  ft  Ferrous  Sulphate.— Measure,  with  a  pip- 
ette, 5  c.  c.  of  ft  FeSO4,  into  a  beaker,  add  some  dilute 
H2SO4  and  run  in  ft  K2Cr207,  till  a  drop,  brought  in  con- 
tact with  a  drop  of  the  indicator  on  a  marble  or  porcelain 
slab  fails  to  give  a  blue  color. 

Reaction. 
6FeS04  +  7H8S04  +  K2Cr2OT  =  3Fe8(SO4)s  +  K2SO< 

+  Cr2(S04)3  +  7H20. 

(6)  With  ft  Sodium  Hyposulphite — according  to  direc- 
tions given  under  titration  of  permanganate  (c). 

ft  IODINE. 

Iodine  =  126.5.    12.65  grms.  per  litre. 

Place  in  a  glass  stoppered  bottle  about  three  grms.  and 
weigh.  (The  bottle  must  be  kept  closed  while  weighing 
to  prevent  the  iodine,  which  is  very  volatile,  from  injur- 
ing the  balance).  Prepare  a  solution  of  KI  by  taking  ten 
grms.  and  dissolving  it  in  100  c.  c.  of  water;  transfer  the 
iodine  to  the  graduated  cylinder,  rinsing  the  weighing 
bottle  with  this  solution ;  shake  the  cylinder  till  the  iodine 
is  dissolved. 

To  calculate  the  dilution. 

12.65  :  1000  :  :  wt.  taken  :  x.    x  =  dilution. 

This  solution  changes  after  standing  some  time,  and 
must  therefore  be  often  tested. 

TITRATION  OF  IODINE. 

(a)    With  &  Sodium  Hyposulphite— Take  5  c.  c.  of  ft 


28  VOLUMETRIC  ANALYSIS. 

sodium  hyposulphite,  add  a  few  drops  of  starch  indicator, 
and  run  in  the  iodine  solution  till  one  drop  produces  a 
permanent  blue  color.  (The  solution  must  not  be  heated). 

Reaction. 
2Na2S2O3  +  21  =  2NaI  +  Na2S4O6. 

(c)  With  A  Arsenious  Add.—  Take  5  c.  c.,  of  T^  arsen- 
ious  acid,  add  starch  indicator  and  titrate;  (as  given  under 
(a)  ). 

Reaction. 


As2O3  +  2Na2O  -f  41  =  As2O5 

STARCH  INDICATOR. 

Take  one  part  of  starch,  triturate  in  a  mortar  with 
cold  water,  then  pour  over  it  200  parts  of  boiling  water, 
and  boil  a  short  time;  allow  it  to  cool  and  settle,  then 
draw  off  the  clear  liquor  for  use. 

$j-  FERROUS  SULPHATE. 

Weigh  out  one  or  two  grms.  of  clean,  fine,  soft,  iron 
wire,  dissolve  in  dilute  H2SO4  by  the  aid  of  heat,  in  a 
small  flask  closed  with  a  cork  through  which  passes  a 
glass  tube  drawn  out  to  a  fine  point  at  the  upper  end; 
when  dissolved,  transfer  to  the  graduated  cylinder,  and 
dilute  according  to  the  following  proportion: 

5.6  :  1000  :  :  wt.  taken  :  x.    x  —  dilution. 

Since  pure  iron  wire  cannot  readily  be  obtained,  it  is  nec- 
essary to  ascertain  the  per  cent,  of  impurity  and  deduct 
the  same  from  the  amount  taken. 

The  Ammonio-ferrous  Sulphate  is  a  good  and  conven- 
ient substitute  for  the  ferrous  sulphate.  The  formula  of 
this  salt  is,  Fe(]SrH4)8(SO4)2,  6H2O,  consequently  it  con- 
tains one-seventh  of  its  weight  of  iron. 

Preparation.—  To  50  c.  c.  of  water  add  12  c.  c.  of  strong 
H2S04  and  divide  into  two  equal  portions.  Place  one 
portion  in  a  flask,  add  a  slight  excess  of  small  nails,  free 
from  rust,  and  allow  the  flask  to  stand  in  a  warm  place 


VOLUMETKIC  ANALYSIS.  29 

over  night.  In  the  morning  add  enough  water  to  restore 
the  solution  to  its  original  bulk,  warm  at  70°  C.,  till  the 
evolution  of  hydrogen  has  ceased  or  nearly  ceased,  add- 
ing water  from  time  to  time  if  necessary;  now  filter 
through  a  warm  funnel  into  a  warm  dish. 

To  the  other  portion  add  ammonium  carbonate  in 
lump  till  violent  action  ceases,  then  warm  and  add  it  in 
powder  till  the  solution  is  neutral,  and  filter  if  necessary. 
Mix  the  two  solutions  in  a  beaker,  heat  to  80°  or  90°  C, 
mix  thoroughly,  add  a  few  drops  of  H2SO4  if  the  solution 
is  not  already  acid,  then  pour  into  a  porcelain  dish,  and 
stir  till  cold.  Allow  to  stand  some  hours,  decant  the 
mother-liquor,  transfer  the  bluish-white  powder  to  a  fun- 
nel and  apply  suction;  wash  three  or  four  times  with 
alcohol,  and  then  dry  on  filter-paper,  without  heat,  till 
the  powder  will  run  like  sand.  Preserve  in  ground-stop- 
pered bottles. 

&  AMMONIO- FERROUS  SULPHATE.    . 

Take  3.92  grms.,  add  5  c.  c.  H2SO4,  and  dissolve  in 
water,  and  dilute-  to  100  c.  c. 

For  testing  the  strength  of  permanganate  or  bichro- 
mate solutions,  take  about  0.5  grm.  of  the  iron  salt,  dis- 
solve in  water  acidulated  with  H2SO4  and  titrate. 

^  SODIUM  HYPOSULPHITE. 

Na2S2O3,  5H2O  =  248.    24.8  grms.  per  litre. 

First  powder  and  dry  a  quantity  of  the  salt  by  press- 
ing between  folds  of  blotting  paper,  then  weigh  24.8  grms., 
dissolve  in  water,  and  dilute  to  one  litre. 

Directions  for  titrating  are  given  under  "  T^  Perman- 
ganate and  Iodine." 

The  solution  should  be  kept  in  the  dark;  after  a  time 
it  undergoes  a  slight  amount  of  oxidation,  and  sulphur 
deposits  on  the  bottle.  This  it  is  said  can  be  prevented 
by  adding  two  grms,  of  Ammonium  Sesquicarbonate  or 
a  little  caustic  soda  to  a  litre  of  the  solution. 


30  VOLUMETRIC  ANALYSIS. 

ft  ARSENIOITS  ANHYDRIDE. 

As2Os  =  198  -5-  4  =  49.5.    4.95  grms.  per  litre. 

Weigh  approximately  3  grms.,  place  it  in  a  flask,  add 
25  grms.  of  pure  Sodium  Bicarbonate,  and  about  250  c.  c. 
of  water;  boil  till  dissolved,  cool,  decant  the  clear  solution 
into  a  graduated  cylinder;  titrate  with  ft  Iodine,  and 
calculate  the  dilution  required  to  make  an  ft  solution  of 
the  As2O8.  After  diluting  again  titrate  with  ft  Iodine 
to  make  certain  of  its  accuracy. 


OXIDE  OF  IRON. 

To  be  titrated  for  Fe  by  ft  KMnO4. 
ft  factor  of  Fe  =  .0056. 

Weigh  out  0.5  grm.,  place  it  in  a  porcelain  dish,  add 
strong  HC1,  mix  thoroughly,  cover  with  a  clock  glass 
and  heat  at  100°  C.,  till  dissolved;  cool,  then  add  strong 
H2S04  and  evaporate  till  S03  fumes  appear,  cool,  add 
water  and  dilute  the  solution  to  a  given  number  of  c,  c., 
measure  10  or  20  c.  c.  into  a  beaker,  dilute  with  water, 
add  Zn,  and  enough  112804  to  produce  a  brisk  evolution 
of  hydrogen;  warm  and  allow  the  action  to  go  on  until 
the  Fe2O3  is  all  reduced  to  FeO,  remove  the  Zn,  and 
heat  till  the  bubbles  are  all  removed,  then  titrate  with 
ft  KMn04. 

Note  :  The  Zn  should  always  be  tested  to  ascertain  if 
it  has  reducing  power;  and  if  it  has,  this  must  be  deter- 
mined, and  the  amount  of  KMnO4  which  a  given  weight 
will  reduce,  deducted  from  the  total  KMnO4  used. 

Boxl. 

IRON  ORE. 

To  be  titrated  for  Fe  by  ft  Na2S2O8. 
ft  factor  of  Fe  =  .0056. 

Pulverize  the  sample  very  fine  with  an  agate  mortar, 
dry  at  100°  C.  then  weigh  0.5  grm.,  digest  in  a  flask  with 


VOLUMETRIC  ANALYSIS.  31 

strong  HC1  at  100°  C.  When  dissolved,  cool,  transfer  to  a 
graduated  cylinder  and  dilute  to  200  c.  c.:  take  5  c.  c.,  dilute 
largely,  add  3  c.  c.  of  a  one  per  cent,  solution  of  Copper 
Sulphate,  and  two  drops  of  KCyS,  now  titrate  with  fa 
Na2SzO3  until  the  red  color  disappears. 

The  solution  must  be  cold,  and  must  remain  clear. 

The  copper  is  alternately  reduced  by  the  Hyposulphite 
and  oxidized  by  the  Fe,Cl6. 

Also  titrate  the  same  solution  for  Fe  in  the  following 
manner:  Take  5  c.c.boil  and  run  into  it  from  a  burette  a 
solution  of  SnCl2  (50  grms.  to  500  c.  c.  of  %  strength  HC1) 
one  drop  at  a  time,  till  all  the  Fe2O3  is  reduced  to  FeO, 
and  the  tin  solution  is  in  slight  excess;  now  add  10  c.  c. 
of  a  cold  saturated  solution  of  HgCl2,  (60  grms.  per  litre) 
shake  well,  and  titrate  with  fa  K2Cr207. 

Box  8. 

FERROUS  AND  FERRIC  OXIDES. 

To  be  titrated  for  FeO,  fa  factor  -  .0072 
To  be  titrated  for  Fe2O3,  fa  factor  =  .008 

Pulverize  in  an  agate  mortar,  and  dry  at  100°  C.;  weigh 
out  1  grm.,  place  it  in  the  weighing  flask,  add  strong  HC1 
close  the  flask  with  a  cork,  through  which  passes  a  glass 
tube;  digest  at  100°  C  till  dissolved,  cool,  and  dilute  to  the 
mark. 

Measure  out  10  c.  c.  and  titrate  as  quickly  as  possible 
with  -fa  K2Cr2O7;  this  will  give  the  FeO. 

Measure  out  10  c.  c.;  reduce  with  SnCl2  and  titrate  total 
Fe.  Deduct  the  amount  of  FeO  obtained  by  the  first  tit- 
ration  and  figure  the  remainder  as  Fe2O3. 

Sox  9. 

ARSENIOUS  ANHYDRIDE •=  198. 

fa  factor  of  As2O3  =  .00495 
fa  factor  of  As  =  .00375 

Weigh  out  0.2  grm.,  and  dissolve  it  in  50  c.  c.  of  a  sat- 
urated solution  of  pure  sodium  bicarbonate,  with  the  aid 


32  VOLUMETBIG  ANALYSIS. 

of  heat;  cool  and  dilute  to  a  given  number  of  c.  c.;  meas- 
ure out  samples,  and  titrate  with  ft  iodine  and  starch. 

This  method  gives  the  As2O3  only  and  not  the  As2O5 
which  is  always  present  in  the  commercial  article.  If 
the  As2O5  is  to  be  estimated  it  must  first  be  reduced  to 
As2O3  by  SO2  gas. 

Bottle  10. 

TINCTURE  OF  IODINE. 

Iodine  =  126.5.    ft  factor  =  .01265. 

First  test  the  sample  to  see  whether  it  is  a  simple  or 
compound  tincture  by  adding  water  to  a  small  portion, 
which  will  produce  a  precipitate  in  the  former  but  not  in 
the  latter.  If  it  is  a  simple  tincture,  dry  the  weighing 
flask,  then  put  into  it  a  few  c.  c.  of  the  tincture  and  weigh; 
now  add  some  KI  solution,  and  dilute  to  the  mark.  If  it 
is  a  compound  tincture,  weigh  without  the  above  precau- 
tions, and  dilute  with  water. 

Now  measure  out  samples  and  titrate  with  ^  Na2S2O3, 
also  with  ft  As2O3. 

Bottle  11. 

BLEACHING  POWDER  =   Ca3H6O6Cl4. 

ft  factor  =  .003537. 

Commercial  bleaching  powder  consists  of  a  mixture  of 
calcium  hypochlorite  (the  true  bleaching  agent),  calcium 
chloride  and  nydrate,  and  in  some  cases  calcium  chlorate. 

It  is  generally  valued  and  sold  in  this  country  by  its 
per-centage  of  chlorine. 

Weigh  5  grms.  and  triturate  it  in  a  porcelain  mortar 
with  water;  pour  the  milky  liquid  into  a  graduated  cylin- 
der, triturate  the  residue  with  water,  and  repeat  the  oper- 
ation till  all  has  been  transferred  to  the  cylinder,  then 
dilute  to  500  c.  c.;  shake  well  and  take  of  the  milky  liquid 
10  c.  c.,  and  run  into  it  an  excess  of  ft  As2O3  (20  c.  c.), 
shake  well,  add  starch  indicator  and  titrate  back  the 
excess  of  Ass03  with  ft  Iodine, 


VOLUMETRIC  ANALYSIS.  33 

BY  PRECIPITATION. 

&  SILVER  NITRATE. 

AgN03  -  169.66.    16.966  grms.  per  litre. 
Dissolve  4.2418  grms.  in  water  and  dilute  to  250  c.  c. 

$5-  SODIUM  CHLORIDE. 

ZSTaCl  =  58.37.    5.837  grms.  per  litre. 
Dissolve  2.918  grams,  in  water  and  dilute  to  500  c.  c. 

ffr  AMMONIUM  SULPHOCYANATE, 

KH4SCN  =  76.    7.6  grms.  per  litre. 

This  solution  cannot  be  prepared  by  weighing  the  salt, 
owing  to  its  diliquescent  nature;  therefore  dissolve  about 
4  grms.  in  400  c.  c.  of  water  and  adjust  by  titrating  with 
•&  AgNO3,  (see  directions  given  below). 

Indicators. 

(a)  Normal  Potassium  Chromate  —  (K2CrOJ,  (it  must 
be  free  from  chlorine).  Make  a  cold  saturated  solution; 
it  can  be  used  only  with  neutral  solutions  and  in  titrat- 
ing chlorine  in  chlorides. 

(6)  Ammonia  Ferric  Alum,— Make  a  saturated  solu- 
tion. 

TITRATION  OF  SILVER  NITRATE. 

(1)  With  &  Sodium  Chloride.— Place  5  c.  c.  of  •&  NaCl 
in  a  beaker,  add  2  drops  of  indicator  (a),  and  titrate  with 
3%  AgNO3   till  a  faint,   permanent   red   precipitate  is 
formed. 

(2)  With  &  Ammonium  Sulphocyanate. — Place  5  c.  c. 
of  ^  AgN03  in  a  beaker,  add  3  drops  of  indicator  (6)  and 
about  1  c.  c.  of  HN03,  titrate  with  &  sulphocyanate  till  a 
faint  permanent  red  color  is  produced. 

Bottle  12. 

SODIUM  CHLORIDE. 

To  be  titrated  for  Cl.    T\  factor  of  Cl  =  .003537 
4 


34  VOLUMETEIC  ANALYSIS. 

Dissolve  0.5  grm.  in  the  weighing  flask  with  water, 
dilute  to  the  mark;  measure  out  several  samples  and 
titrate  with  -ft  AgN03,  using  indicator  (a). 

Bottle  13. 

SILVER  NITRATE  SOLUTION. 

To  be  titrated  for  Ag.    ft  factor  of  Ag  =  .010766 

(1)  Take  3-5  grms.  of  solution,  and  titrate  with  ft  sul- 
phocyanate,  without  dilution. 

(2)  Take  known  weight  of  silver  solution  in  a  beaker; 
run  in  excess  of  ft  NaCl;  add  Indicator  and  titrate  back 
with  T\  Ag  N03. 

Bottle  14. 

Hydrocyanic  Acid,  HCN  =  27.    ft  factor  =  .0054 
Weigh  about  5  grms.  in  a  tightly  stoppered  flask,  then 
add  a  solution  of  KHO  till  decidedly  alkaline  and  dilute 
largely;  now  run  into  the  whole  solution,  ft  AgNO3  till  a 
slight  permanent  precipitate  remains. 

Reaction. 

2KCy  +  AgN03  =  KCy,AgCy  +  KNO3 
(no  precipitate),  +  AgNo3  =  precip  =  2AgCy  + 


GRAVIMETRIC  SEPARATIONS. 

Boxl. 
SILVER  COIN  =  Ag  +  Cu  (+  traces  of  Au  &  Pb). 

Clean  the  sample  by  washing  with  KHO,  or  N 
then  with  water,  dry,  cool,  and  weigh;  place  it  in  the 
weighing  flask,  dissolve  with  HN03  (avoiding  an  excess), 
cool,  and  dilute  to  the  mark. 

Take  30  c.  c.  of  this  solution,  heat  to  70°  C.,  and  add  HC1 
as  long  as  a  precipitate  is  formed  (a  large  excess  of  HC1 
must  be  avoided);  stir  thoroughly,  let  it  stand  in  a  dark 
place  till  the  precipitate  has  fully  settled,  filter  by  decan- 
tation,  wash  first  with  hot  water  acidulated  with  HN"O3. 
then  with  pure  water,  dry,  etc.  (See  page  10). 

Return  the  per  cent,  of  Ag. 

Boil  the  filtrate,  remove  the  lamp,  add  gradually  KHO 
solution  till  strongly  alkaline,  boil  for  15  minutes,  filter 
and  wash  by  decantation  with  hot  water,  until  the  wash 
water  gives  no  precipitate  with  Ag^TO3.  Dry,  ignite  and 
weigh.  Result  =  CuO. 

Return  the  per  cent,  of  Cu. 

Titrate  a  portion  of  the  original  solution  with  ^  sul- 
phocyanate,  as  a  check  upon  the  gravimetric  determina- 
tion of  the  silver. 

Box  2. 
BRASS  =  Cu.  -f  Zn.  (-J-  traces  of  Sn.  and  Pb.). 

Take  about  0.2  grm.,  dissolve  in  HN03,  evaporate  to 
dryness,  moisten  with  HNO3,  add  water,  and  heat.  If 
there  is  a  residue,  filter. 

Res.  (a)  —  SnO2.  Dry,  ignite  and  weigh,  result  =. 
SnO2;  return  the  per  cent,  of  Sn. 


36         GRAVIMETRIC  SEPARATIONS. 

Filt.  (a)  =  Cu.  Zn.  Pb.;  add  3  c.  c.  H2SO4,  evaporate  in 
a  porcelain  dish  till  copious  white  fumes  of  SO3  are  given 
off,  cool,  add  50  c.  c.  of  cold  water;  if  there  is  a  residue, 
add  20  c.  c.  of  alcohol,  filter  and  wash  with  dilute  alcohol 
<1  to  4). 

Pp.  (6)  =  PbSO4,  dry,  ignite,  cool,  add  a  few  drops  of 
H2SO4,  cover  the  crucible,  heat  moderately  till  excess  of 
H2SO4  is  driven  off;  then  ignite  strongly.  Kesult  = 
PbSO4;  return  the  per  cent,  of  Pb. 

Filt.  (b)  =  Zn.  Cu.;  heat  on  the  water  bath  until  the 
alcohol  is  expelled,  cool,  dilute  to  100  c.  c.,  add  1  c.  c.  H2- 
SO4,  boil  then  add  gradually  a  solution  of  sodium  hypo- 
sulphite (avoiding  a  large  excess)  as  long  as  a  black  pre- 
cipitate continues  to  form ;  filter,  and  wash  thoroughly 
with  hot  water.* 

Pp.  (C)  =  Cu2S,  dry,  remove  the  precipitate  from  the 
filter,  incinerate  the  filter  thoroughly,  add  the  precipitate, 
and  an  equal  bulk  of  sulphur,  mix  thoroughly,  cover  the 
crucible,  ignite,  moderately  at  first,  finishing  with  a  dull 
red  heat;  all  the  sulphur  will  be  burned  off  in  about  5 
minutes. 

Result  =  CuO,  Cu2S;  a  mixture  of  the  oxide  and  sul- 
phide. CuO  =  79.98  per  cent.  Cu.  and  Cu2S  =  79.87  per 
cent.  Cu.  Return  the  per  cent,  of  Cu.  treating  the  result 
as  Cu2S. 

Filt.  (c)  =  Zn.;  add  HNO3,  evaporate  to  a  small  bulk, 
filter  to  remove  the  separated  sulphur,  transfer  the  fil- 
trate to  a  large  porcelain  evaporating  dish,  boil,  add  a 
solution  of  NaHCO3  till  strongly  alkaline,  boil,  wash  by 
decantation,  and  afterwards  on  the  filter  with  hot  water. 

Pp.  (d)  =  ZnCO3,  dry,  incinerate  the  filter,  add  the 
precipitate  and  ignite.  Result  =  ZnO.  Return  the  per 
•cent,  of  Zn. 

Sox  3. 

PARIS  GREEN. 

Aceto-arsenite  of  copper  =  3  (CuOAs2O3),  Cu(C2H302)2. 
*Fresenius  459,  Classen  51. 


GRAVIMETRIC  SEPARATIONS.  37 

Weigh  out  1  grm.,  add  cold  NH4OH,  and  stir  till  all 
the  green  particles  have  dissolved.  If  there  is  a  residue, 
filter  through  counterpoised  filters. 

Res.  (a)  =  insoluble  matter,  dry  at  100°  C.  and  weigh. 
Return  the  per  cent. 

Filt.  (a)  =  Cu.  As;  add  HC1  till  nearly  neutral,  then 
yellow  ammonium  sulphide,  and  digest  at  a  moderate  heat 
for  one-half  hour,  decant  the  supernatant  liquid  on  a  fil- 
ter, and  to  the  residue  add  more  ammonium  sulphide  and 
digest;  filter  and  wash  with  water,  to  which  a  little  am- 
monium sulphide  has  been  added. 

Pp.  (6)  =  CuS;  dry,  ignite  and  weigh. 
Result  =  CuO,  CiigS.    Return  the  per  cent,  of  Cu. 

Filt.  (b)  =  As;  add  dilute  HC1,  cautiously,  to  acid 
reaction;  warm,  pass  H2S  gas  for  one  half  hour;  filter, 
(reject  the  filtrate)  dissolve  the  precipitate  with  KHOy 
filter  to  remove  the  free  sulphur,  then  pass  into  the  solu- 
tion chlorine  gas,  for  one  hour,  (the  solution  must  be  kept 
alkaline),  now  acidulate  with  HC1  (the  solution  must 
remain  clear),  add  NH4OH  in  excess,  and  then  magnesia 
mixture  in  excess,  let  it  stand  12  hours,  filter  through 
tared  with  filters,  wash  with  a  mixture  of  1  part  NH4OH 
and  3  parts  water. 

Pp.  (c)  =  MgNH4AsO4  +  6H2O;  dry  at  102°  to  103° 
C,  and  weigh;  repeat  the  drying  till  constant  weight  is 
obtained. 

Result  =  (MgNH4AsO4)2,  H2O. 
Return  the  per  cent,  of  As. 

Box  4. 

BAKING  POWDER. 

The  value  of  a  powder  depends,  first,  upon  the  amount 
of  CO2,  which  a  given  weight  will  give  off  when  dissolved 
in  water;  second,  upon  the  solution  thus  formed  being 
neutral;  third,  upon  its  purity. 


38  GRAVIMETRIC  SEPARATIONS. 

Composition  of  some  of  the  baking  powders  in  common  use. 

No.  3. 


No.  1. 

Corn  Starch 4  % 

Bitartrate  of  Potash.  58  " 
Bicarbonate  of  Soda.  38  " 


Flour 37.5 

Tartaric  Acid 25 

Bicarbonate  of  Soda  37.5 


No.  2. 

Corn  Starch 37 

Tartaric  Acid 10 

Bicarbonate  of  Soda.  30 

Sesqui  Carb.  Am 6 

Alum  . .  .17 


No.  4. 

Flour 20 

Bitartrate  of  Potash.  51 

Tartaric  Acid 3 

Bicarbonate  of  Soda.  24 
.Carbonate  of  Am,. .      2 


These  are  known  as  tartaric  acid  or  cream  of  tartar 
powders;  the  alum  in  No.  3  is  probably  used  to  make  the 
bread  white  and  performs  no  other  part  in  the  powder. 

There  are,  besides  the  foregoing  powders,  those  which 
have  no  tartaric  acid. 

First,  the  alum  powders,  which  should  always  be 
rejected. 

Second,  the  phosphate  powders,  which  are  said  to  be 
among  the  best. 

The  following  directions  apply  only  to  the  tartaric 
acid  or  cream  of  tartar  powder,  which  should  always  be 
tested  for  adulterations,  especially  alum;  and  if  present 
it  should  be  estimated. 

(1)  Estimation  of  Starch  or  Flour— Take  0.5  grm., 
add  cold  water  and  shake  till  the  powder  is  dissolved, 
filter  through  tared  niters,  dry  at  100°  C,  and  weigh. 

The  filtrate  after  boiling  should  give  a  neutral  reaction 
when  tested  with  litmus. 

If  it  gives  an  alkaline  reaction,  which  is  often  the  case, 
titrate  this  excess  of  alkali  with  -fa  H2S04,  and  calculate 
the  excess  as  NaHCO3. 

(2)  Estimation  of  C02.—(a)   Use  the  ordinary  car- 
bonic acid  apparatus,  and  displace  the  CO2  with  dilute 
H2SO4;  this  gives  the  total  CO2. 


GRAVIMETRIC  SEPARATIONS.  39 

(6)  Determine  the  C02  which  the  powder  will  give  off 
when  dissolved  in  water  using  the  same  apparatus;  heat 
the  flask  to  80°  C  at  the  last,  and  cool  before  weighing; 
this  gives  the  available  C02. 

(3)  Estimation  of  Soda  and  Potash.— First  test  for 
potash  with  the  flame.  Take  1  grin,  incinerate  thoroughly 
in  a  porcelain  evaporating  dish  till  the  carbon  is  all  burnt 
off,  (the  mass  must  not  be  fused).    Extract  the  residue 
with  hot  water,  filter  into  a  flask  (the  filtrate  should  not 
exceed  30  c.  c.)    If  there  is  no  potash  present  titrate  this 
filtrate  with  ^  H2S04  for  soda.    If  potash  is  present, 
place  the  flask  containing  this  filtrate  over  the  lamp,  boil, 
and  while  boiling  add  gradually  from  a  burette  normal 
tartaric  acid,  until  the  red  color  of  the  indicator  fails  to 
reappear  after  boiling  two  minutes,  now  add  as  much 
more  tartaric  acid,  cool  the  solution,  etc.    (See  page  21). 

(4)  Estimation  of  Tartaric  Acid. — Since  this  cannot 
be  estimated  advantageously  by  any  direct  process,  we 
resort  to  an  indirect  method  by  calculation. 

If  the  tartaric  acid  exists  in  the  powder  in  the  form  of 
bitartrate  of  potash,  the  following  proportion  will  give 
the  amount  of  that  salt  present. 

KHO  ;  C4H5K06  :  :  the  per  cent  of  KHO  :  x.    x  =  the 
per  cent,  of  bitartrate  of  potash. 

If  there  is  no  potash  present  then  we  may  conclude 
that  the  tartaric  acid  exists  as  such  in  the  powder,  and 
its  per  cent,  may  be  thus  calculated.  Deduct  from  the 
total  NaHO  as  found  by  (3),  the  excess,  if  any,  of  NaHO 
as  found  by  (1);  the  difference  represents  the  amount  of 
NaHO,  neutralized  by  the  tartaric  acid.  Placing  it  in 
the  form  of  a  proportion,  we  have. 

2(NaHO)  :  C4H6O6  :  :  the  per  cent,  of  NaHO  :  y.    y  = 
per  cent,  of  tartaric  acid. 

Return  the  ingredients  as  found  by  the  foregoing  direc- 
tions as  follows: 


40  GKAVIMETKIC  SEPARATIONS. 

Starch  or  Flour per  cent. 

Total  Bicarbonate  of  Soda  (NaHC03) "  " 

Excess  of       "         "      "            "         «  « 

Bitartrate  of  Potash  (C4H5KO6)  or "  " 

Tartaric  Acid  (C4H6O6) "  " 

Also  report  what  if  any  impurities  are  present. 


WATER  ANALYSIS. 

REAGENTS  AND  APPARATUS. 

[A .]  Reagents  for  the  estimation  of  nitrogen,  present 
as  ammonia  (NHS}. 

(1)  Nessler  Reagent— Take  5  grms.  KI,  dissolve  in  15 
c.  c.  of  water,  add  gradually,  a  cold  saturated  solution  of 
mercuric  chloride  (table  reagent),  till  the  mercuric  iodide 
ceases  to  be  dissolved  on  stirring,  and  a  slight  permanent 
precipitate  remains;  now  add  a  solution  of  caustic  potash,, 
made  by  dissolving  15  grms.  of  solid  caustic  in  30  c.  c.  of 
water;  allow  to  settle  before  using. 

(2)  Dilute  Solution  of  Ammonia. — Dissolve  3.15  grms. 
of  NH4C1  in  one  litre  of  water.    Take  10  c.  c.  of  this  solu- 
tion and  dilute  to  one  litre.    .1  c.  c.  of  this  solution  con- 
tains .00001  grm.  of  NH3. 

(3)  Dry  Sodium  Carbonate. — Heat  about  3  grms.  of 
anhydrous  sodium  carbonate  in  a  porcelain  dish  for  one 
hour,  at  a  bright  red  heat,  cool,  pulverize  and  place  in  a 
ground  stoppered  bottle. 

(4)  Apparatus.— Four  large  test  tubes,  of  the  same 
diameter,  that  will  hold  60  c.  c.  or  more.  Graduate  with  a 
50  c.  c.  mark.  Also  a  glass  tube  with  a  bulb  blown  at  one 
end. 

[J5]  Reagent  for  the  estimation  of  Albumenoid  Am- 
monia. 

(1)  Solution  of  Potassium  Permanganate  and  Potash 
— is  made  by  dissolving  1.  grm.  of  KMnO4,  and  25  grms. 
of  solid  caustic  potash  in  separate  portions  of  water,  mix- 
ing the  solutions  and  diluting  to  125  c.  c. ;  boil  the  solu- 
tion for  one-half  hour,  cool  and  place  in  a  well  stoppered, 
bottle. 

[C]    Reagents  for  determining  hardness. 


42  WATER  ANALYSIS. 

(1)  Solution  of  Calcium  Chloride— Dissolve  1  grm. 
of  finely  powdered  marble,  or  pure  carbonate  of  lime  in  a 
slight  excess  of  dilute  HC1,  and  neutralize  the  excess  of 
acid  by  ammonia,  and  dilute  to  one  litre.    Each  c.  c.  con- 
tains .001  grm.  CaCO3. 

(2)  Soap  Solution. — Dissolve  about  8  grms.  of  white 
castile-soap  (or  any  good  olive-oil  soap)  in  600  c.  c.  of  35 
per  cent,  alcohol,  and  so  dilute  it  that  13  c.  c.  will  produce 
a  permanent  lather  in  70c.c.of  distilled  water  which  con- 
tains 12  c.  c.  of  C.  1.  It  has  been  found  that  70  c.  c.  of  pure 
water  destroy  1  c.  c.  of  standard  soap;  and  since  we  use 
70  c.  c.  of  the  water  under  examination  it  will  destroy  1 
c.  c.  of  soap,  without  any  material  being  present  which 
causes  hardness.    To  compare  the  solutions  proceed  as 
follows: 

Take  12  c.  c.  of  C.  1,  place  it  in  a  200  c.  c.,  flask  and  add 
58  c.  c.  of  pure  water  (12  +  58  =  70);  now  run  in  from  a 
burette  the  soap  solution,  1  c.  c.  at  a  time,  and  shake  the 
flask  after  each  addition,  till  a  lather  is  produced  which 
will  last  five  minutes.  From  the  result  obtained  calcu- 
late the  dilution  required.  Suppose  8  c.  c.  of  the  soap 
solution  were  used  and  there  are  600  c.  c.  remaining  in 
the  graduated  cylinder.  We  must  dilute  the  600  c.  c.  so 
that,  13  c.  c.  will  be  required  instead  of  8  c.  c.  The  follow- 
ing proportion  will  give  the  amount  of  35  per  cent,  alco- 
hol that  must  be  added. 

8:5:  :  600  :  x  =  375  c.  c.  to  be  added  or  600  +  375  = 
975  c.  c.  total  dilution. 

[D]    Reagents  for  determining  Cl,  present  as  chlorides. 

(1)  Silver  Nitrate— Dissolve  4.79  grms.  of  AgNO3  in 
one  litre  of  pure  water;  one  c.  c.  will  precipitate  .001 
grm.  Cl. 

(2)  Yellow  Potassium  Chromate—  Make  a  cold  satur- 
ated solution  (it  must  be  free  from  chlorine). 

COLLECTION  OF  SAMPLES. 

The  amount  to  be  collected  will  depend  upon  the 
nature  of  the  water  and  the  number  of  elements  to  be 


WATER  ANALYSIS.  43 

determined;  two  gallons  as  a  rule  will  be  ample.  Care 
must  be  exercised  in  collecting  the  sample  to  secure  an 
average.  The  bottle,  in  which  the  sample  is  to  be  col- 
lected, should  be  first  thoroughly  cleansed,  and  then 
rinsed  out  with  some  of  the  same  kind  of  water  as  that 
which  is  to  be  analyzed;  after  filling,  it  should  be  closed 
with  a  clean  cork. 

Before  taking  out  a  sample  for  any  of  the  following 
determinations,  the  bottle  should  be  well  shaken,  unless 
otherwise  directed. 

Determination  of  the  Total  Solid  Residue. 

Take  100  c.  c.  and  evaporate  to  dryness  in  a  weighed 
dish,  on  a  water -bath,  then  place  in  an  air-bath  and  heat 
at  104°  C  for  30  minutes,  cool  and  weigh.  Eesult  =  total 
solid  residue. 

A  much  larger  quantity  of  water  will  be  required  in 
most  cases. 

For  the  sake  of  convenience,  convert  all  results  as  fast 
as  obtained  into  parts  per  1,000. 

Determination  of  Chlorine. 

Take  100  c.  c.,  add  a  few  drops  of  D.  2,  and  titrate  with 
D.  1. 

If  good  results  are  not  obtained,  take  500  c.  c.,  concen- 
trate by  evaporation  to  about  50  c.  c.  and  then  titrate. 

Both  solutions  must  be  neutral;  if  acid,  make  neutral 
by  adding  some  carbonate  of  soda. 

Determination  of  Sulphuric  Acid. 

Take  200  c.  c.,  acidify  with  HC1,  boil,  filter,  and  then 
precipitate  with  barium  chloride. 

Determination  of  Inorganic  Constituents. 

Acidulate  one  litre  with  HC1,  and  evaporate  to  dry- 
ness,  moisten  the  residue  with  HOI  and  dissolve  with 
water,  filter. 


44  WATEK  ANALYSIS. 

Res.  (a)  =  SiO2;  dry,  ignite  and  weigh. 

Filt.  (a);  concentrate  by  evaporation,  add  excess  of 
ammonia,  boil,  filter. 

Pp.  (6)  =  Fe2O3— A12O3  and  P2O5.  Dry,  ignite  and 
weigh. 

Filt.  (6);  add  excess  of  ammonium  oxalate,  boil,  let 
stand  six  hours,  filter. 

Pp.  (c)  =  calcium  oxalate,  dry,  ignite  and  weigh. 

Filt.  (c);  concentrate,  cool,  add  a  solution  of  Na2HPO4 
and  NH4OH  in  excess,  let  stand  six  hours,  filter. 

Pp.  (d)  =  Mg2(NH4)2(POJ2.    Dry,  ignite  and  weigh. 

Determination  of  Potash  and  Soda. 

These  are  generally  determined  jointly. 

Take  500  c.  c.  evaporate  to  dryness,  add  0.2  grm.  of 
caustic  baryta,  and  a  little  distilled  water,  and  boil,  filter; 
to  the  filtrate  add  ammonium  carbonate,  boil  and  filter; 
evaporate  this  filtrate  to  dryness  and  ignite  moderately  in 
a  weighed  porcelain  crucible;  remove  the  lamp,  add  solid 
N"H4C1,  and  again  ignite  till  fumes  cease  to  be  given  off 
(use  only  a  moderate  heat)  cool  ard  weigh. 

Kesult  =  KC1,  NaCl,  return  as  Na2O. 

Determination  of  Hardness. 

Take  70  c.  c.  of  the  sample  of  water,  place  it  in  a  200 
c.  c.  flask,  then  run  in  from  a  burette  soap  solution,  1  c.  c. 
at  a  time,  shaking  the  iiask  after  each  addition,  till  a 
lather  is  produced  which  will  last  five  minutes,  and  will 
reappear  on  shaking.  The  number  of  c.  c.  of  soap  solution 
used  represents  the  degrees  of  hardness;  and  each  degree 
stands  for  one  grain  of  CaCO3,  or  its  equivalent,  in  an 
English  gallon. 

The  English  gallon  hold  70,000  grains. 

The  United  States  gallon  holds  58,318  grains. 

If  the  70  c.  c.  require  more  than  16  c.  c.  of  the  soap  solu- 
tion, then  take  35  c.  c.  of  the  water,  and  add  to  it  35  c.  c.  of 
distilled  water,  and  titrate  with  the  soap  solution;  the  re- 
sult multiplied  by  two  will  give  the  degrees  of  hardness. 


WATER  ANALYSIS.  45 

Further  dilution  may  be  required  to  reduce  the  amount 
of  soap  solution  required  below  16  c.  c. 

The  reason  why  this  dilution  is  called  for,  appears  to 
be  that  too  large  a  proportion  of  insoluble  lime-salts,  in- 
terferes with  the  formation  of  a  lather.  When  the  water 
contains  much  Magnesium,  which  is  known  by  the  lather 
having  a  curdy  appearance,  the  reaction  is  slow,  and  the 
water  should  be  diluted  so  much,  that  70  c.  c.  will  require 
less  than  7  c.  c.  of  the  soap  solution.  Time  should  be 
given  for  the  Magnesium  salt  to  form. 

Determination  of  Ammonia. 

Place  a  well  washed  litre  flask  upon  a  piece  of  wire 
gauze,  which  rests  upon  the  ring  of  the  lamp-stand,  and 
then  connect  it  with  a  Liebig's  condenser.  Pour  into 
this  flask  500  c.  c.  of  the  sample  of  water,  and  add  to  it  one 
grin,  of  the  ignited  sodium  carbonate,  connect  the  appa- 
ratus, and  distil  rapidly,  collecting  the  distillate  in  the 
graduated  test  tubes  (A-4).  Distil  until  four  tubes  have 
been  filled  to  the  50  c.  c.  mark,  then  stop  the  operation. 
Now  Nesslerise  the  second  tube,  thus:  add  to  it  2  c.  c.  of 
Kessler  reagent  and  thoroughly  mix;  if  ammonia  is  pres- 
ent, it  will  assume  a  rich  brown  color;  and  the  more  the 
ammonia,  the  deeper  the  color.  Take  another  test  tube, 
(A-4)  place  in  it  1  c.  c.  of  the  dilute  NH^Cl  (A-2),  and  make 
up  to  50  c.  c.  with  distilled  water,  mix  thoroughly,  add  2 
c.  c.  Nessler  reagent  and  again  mix;  compare  this  witn  the 
Nesslerised  distillate.  If  the  colors  are  not  the  same,  the 
made  up  tube  must  be  emptied,  rinsed,  and  refilled,  in  the 
same  order,  adding  more  or  less  of  the  dilute  NH4C1,  as  it 
was  lighter  or  darker  than  the  distillate.  This  operation 
must  be  repeated  till  the  colors  are  the  same.  The  amount 
of  dilute  NH4C1,  added  to  the  made  up  tube  represents  the 
amount  of  NH3  in  the  distillate,  the  Nesslerising  of  this 
second  tube,  is  to  find  out  whether  the  first  tube  can  be 
Nesslerised  as  a  whole,  or  must  be  divided.  If  1  c.  c.  of  the 
dilute  NH4C1  has  been  used,  then  the  first  tube  cannot  be 
Nesslerised  as  a  whole,  for  it  would  give  too  dark  a  color. 


46  WATER  ANALYSIS. 

Therefore  take  10  or  20  c.  c.  of  the  first  tube,  make  it  up  to 
50  c.  c.  with  distilled  water,  mix  thoroughly,  add  2  c.  c. 
Messier  Reagent  and  again  mix;  compare  with  a  made 
up  tube  as  before;  the  result  multiplied  by  the  proper 
factor  will  give  the  total  NH3  in  the  first  tube;  add  to 
this  one-third,  and  we  obtain  the  total  free  ammonia. 

Thus,  10  c.  c.  of  the  first  tube  gave  .00001  grm.  NH8, 
multiplied  by  5  gives  .00005  grm.  in  the  first  tube;  add  to 
this  one-third  and  we  have  .000067  grm.NH3  in  the  500  c.c. 
taken,  or  .000134  grm.  in  a  litre. 

*  ESTIMATION  OF  TOTAL  NITROGEN  OF  NITRATES 
AND  NITRITES. 

Reagents;  (To  be  prepared  shortly  before  required  for 
use). 

(1)  Nessler's  Reagent. 

(2)  Solution  of  NH4C1. 

(3)  Saturated  Solution  H2C2O4,  nearly  free  from  NH3. 
It  should  be  tested  for  NH3  before  using.    A  slight  color 
when  Nesslerized  may  be  disregarded. 

(4)  Zn-Cu  couple.    Fill  a  wide  mouthed  quart  bottle 
with  solution  of  CuSO4  in  H2O,  containing  1.4  to  1.8  per 
cent  CuS04.  Clean  several  strips  of  sheet  Zinc,  four  inches 
by  three-fourths  of  an  inch  in  size,  in  dilute  H2SO4  and 
rinse  carefully  with  pure  H2O.    Introduce  same  into  the 
solution  of  CuSO4  and  close  the  bottle— set  aside  till  the 
Zn  is  well  coated  with  Cu.  Carefully  remove  the  strips  of 
metal  with  forceps  and  wash  with  successive  portions  of 
pure  H2O,  being  careful  not  to  break  off  the  coating  of  Cu. 

Method. 

200  c.  c.  of  the  H2O  under  examination  are  barely 
acidulated  with  Reagent,  3  (above)  and  thoroughly  mixed. 
Divide  into  two  equal  portions  and  place  each  100  c.  c.  in 


"This  method,  called  the  Williams-Blunt  method,  has  been  dis- 
cussed at  length,  by  Dr.  A.  B.  Prescott,  in  the  Pharmaceutical  Era  for 
1887,  and  the  method,  as  herein  given,  is  taken  from  that  source. 


WATER  ANALYSIS.  47 

a  wide-mouthed  bottle.  Into  one  portion  insert  one  of 
the  prepared  Zn-Cu  plates.  Close  both  bottles  and  set 
aside  in  an  atmosphere  free  from  NH3  for  from  24  to  40 
hours. 

Great  care  should  be  taken  to  rinse  all  apparatus  used 
in  pure,  Ammonia — free  H2O.  Take  from  10  to  50  c.c.  from 
each  bottle  (if  the  H20  has  not  over  %  part  per  million 
of  .Nitrogen  of  Nitrates  and  Nitrites,  50  c.  c.'s  may  be 
taken,  but  if  there  be  1  part  per  million,  or  over,  less  of 
the  H2O,  say  10-20  c.  c.  may  be  taken  and  diluted,  with 
pure  H2O,  up  to  50  c.  c.)  care  being  taken  not  to  disturb 
any  sediment  of  precipated  oxalates  which  may  be  in  the 
bottom.  If  less  than  50  c.  c.  be  taken  from  each  bottle,, 
the  same  quantity  must  be  taken  from  each,  and  diluted 
to  50  c.  c.  with  the  same  ammonia — free  H2O. 

Treat  both  portions  of  H2O  with  Nessler's  Eeagent 
(enough  to  serve  the  purpose  after  the  H2C204  has  been 
neutralized)  and  titrate  the  sample,  in  which  Nitrates  and 
Nitrites  have  been  reduced,  against  the  other  sample. 
The  excess  found  in  the  reduced  portion  will  be  the  Nitro- 
gen of  Nitrates  and  Nitrites.  No  account  being  taken  of 
the  Ammoniacal  Nitrogen,  discovered  by  Nesslerizing  the 
unreduced  portion,  which  is  estimated  in  another  ope- 
ration. 

Nitrites  remain  to  be  tested  for— which  may  be  done 
by  use  of  Napthylamine  Hydrochloride  and  Sulphanilic 
acid.  If  Nitrites  are  discovered  their  Nitrogen  is  to  be 
estimated  and  deducted  from  the  amount  found  by  the 
last  operation.  The  color  titration  of  Nitrites  with  Nap- 
thylamine hydrochloride  is  a  valuable  method,  and  but 
little  practice  in  comparison  of  known  solutions  is  neces- 
sary to  render  the  operator  comparatively  expert. 

The  results  of  the  above  determinations  should  be 
calculated  and  reported  as  (1)  Nitrogen  of  Nitrates,  and 
(2)  Nitrogen  of  Nitrites. 

DETERMINATION  OF  ALBUMENOID  AMMONIA. 

From  the  500  c.  c.  of  water  taken  we  have  distilled  oft 


48  WATER  ANALYSIS. 

200  c.  c.  for  the  estimation  of  free  Ammonia;  in  the  re- 
maining 300  c.  c.  we  estimate  the  "  organic  "  or  albumen- 
old  Ammonia,  as  follows: 

Take  50  c.  c.  of  Permanganate  solution  (B-l)  and  add 
to  it  200  c.  c.  of  pure  ammonia-free  water;  distill  till  the 
distillate  gives  no  color  with  Nessler's  Reagent.  Then 
add  to  this  solution,  in  the  retort,  the  300  c.  c.  of  the  water 
under  examination  and  distill  for  albumenoid  Ammonia. 
Collect  the  whole  distillate,  of  150-200  c.  c.,  mix  thor- 
oughly, measure  and  take  portions  of  10-100  c.  c.  (accord- 
ing to  the  amount  of  NH3)  and  Nesslerize. 

By  the  above  dilution  of  the  KMnO4  solution  it  gives 
up,  upon  distillation,  the  small  amount  of  Ammonia 
which  it  otherwise  would  retain  and  which  would  of 
course  vitiate  the  result. 

Reports. 

Eesults  obtained  are  generally  reported  as  "  parts  per 
million "  and  also  as  "  grains  per  gallon."  The  United 
States  gallon  contains,  at  60°  F.,  58,318  grains  of  distilled 
water.  To  convert  "grammes  per  Litre"  into  "grains  per 
gallon,"  multiply  by  58,318  and  divide  by  1,000. 

Eeport  "free  Ammonia"  and  "albumenoid  Ammonia"; 
also,  "Nitrogen  of  Nitrates"  and  "Nitrogen  of  Nitrites." 


METHODS    OF    ESTIMATING  THE    ORGANIC   IM- 
PURITIES  IN   WATER  WITHOUT   GAS 
APPARATUS. 

THE  OXYGEN  PROCESS. 

Reagents. 

(a)  Standard  Solution  of  Potassium  Permanganate. 
— Dissolve  0.395  grms.  of  potassium  permanganate  in  1 
litre  of  water.    Each  c.  c.  contains  0.0001  grm.  of  avail- 
able oxygen. 

(b)  Standard  Solution  of  Sodium  Hyposulphite.— 


WATEK  ANALYSIS.  49 

Dissolve  3.068  grms.  of  the  salt  in  1  litre  of  water.    1  c.  c. 
=  1  c.  c.  of  the  permanganate  solution. 

(c)  Solution  of  Potassium  Iodide.— One  part  of  the 
pure  salt,  recrystallized  from  alcohol,  dissolved  in  ten 
parts  of  water. 

(d)  Dilute  Sulphuric  Acid— One  part  by  volume  of 
pure  sulphuric  acid  is  mixed  with  three  parts  by  volume 
of  water,  and  solution  of  potassium  permanganate  added 
until  the  whole  retains  a  very  faint  pink  tint,  after  warm- 
ing to  80°  F  for  four  hours. 

(e)  Starch  Indicator,  (see  page  20). 

Determination  of  the  Oxygen  Absorbed  by  the  Water. 

Select  a  half  litre  glass-stoppered  flask  and  clean  thor- 
oughly with  H2S04  and  water.  Put  250  c.  c.  of  the  water 
into  it,  stopper  tightly  and  immerse  in  a.  water  or  air 
bath  until  the  temperature  rises  to  27°  C.  Now  add  to  it 
10  c.  c.  of  the  sulphuric  acid  (Sol.  d),  and  then  10  c.  c.  of 
the  standard  permanganate  (Sol.  a).  Stopper  tightly  and 
allow  it  to  remain  at  27°  C,  for  4  hours,  remove  and  add 
the  solution  of  potassium  iodide  till  the  pink  color  disap- 
pears, then  shake  thoroughly  and  titrate  with  hyposul- 
phite solution  until  the  yellow  color  is  nearly  distroyed, 
then  add  a  few  drops  of  starch  indicator,  and  continue 
the  titration  till  the  blue  color  is  just  discharged.  The 
c.  c.  of  KMnO4  taken,  less  the  c.  c.  of  hyposulphite  used 
—  the  c.  c.  of  KMnO4  reduced.  Should  the  permanganate 
color  fade  rapidly  during  the  four  hours,  other  measured 
quantities  must  be  added  from  time  to  time. 

The  permanganate  and  hyposulphite  solutions  must 
be  compared  often,  and  a  correction  factor  used  if  neces- 
sary in  the  titration. 

CONCLUSIONS. 

The  purity  of  the  water  is  indicated  by  the  amount  of 
Oxygen  absorbed  from  the  permanganate  by  100,000.  parts 
of  H2O.  The  following  figures  (which  must  be  considered 
5 


50  WATER  ANALYSIS. 

as  of  questionable  value)  have  been  given  in  connection 
with  the  foregoing  process: 

"  Water  of  great  organic  purity  absorbs  0.05  parts  of 
Oxygen." 

"Water  of  medium  purity  absorbs  0.05  to  0.15  parts  of 
Oxygen." 

"Water  of  doubtful  purity  absorbs  0.15  to  0.2  parts  of 
Oxygen." 

"  Impure  water  absorbs  0.2  or  more." 


Regarding  the  foregoing  process  as  a  means  of  definite 
decision  as  to  the  sanitary  character  of  a  water,  it  is  now 
generally  conceded  that  alone  it  is  of  no  value,  but  should 
always  be  considered  as  simply  an  auxiliary  estimation, 
to  be  considered  together  with  the  estimation  of  saline 
constituents,  free  and  albumenoid  ammonia,  Nitrates 
and  Nitrites,  etc.,  etc. 

In  concluding  this  section  concerning  Water  Analysis 
it  is  necessary  to  state  that  the  interpretation  of  the 
results  of  an  analysis  of  water  is  a  matter  of  far  too  ex- 
tensive a  character  for  the  scope  of  this  book,  and  it  will 
not  be  attempted,  but,  with  a  few  of  the  elementary  con- 
siderations necessary  in  forming  an  idea  of  the  character 
of  a  water,  the  subject  will  be  left  to  the  student,  as  one 
which  requires  a  vast  amount  of  study  and  research. 

In  the  examination  of  a  water,  its  source  should  be 
known— whether  from  a  cistern,  well  or  hydrant;  also, 
the  proximity  of  any  possible  source  of  contamination,  the 
geological  character  of  the  country  and  the  character  of 
the  soil  and  sub-soil.  Un-polluted  spring  water  usually 
contains  less  than  one  part  of  Chlorine.  Sewage  generally 
contains  from  10  to  14  parts  of  Chlorine. 

The  amount  of  Albumenoid  Ammonia  is  of  great  im- 
portance, since  it  indicates  the  presence  of  undecomposed 
animal  or  vegetable  matter. 

The  free  NH3,  the  Nitrates  and  Nitrites  may  be  con- 
sidered harmless  in  themselves;  yet,  as  being  products  of 


WATER  ANALYSIS.  51 

the  oxidation  of  organic  matter,  they  indicate  the  possi- 
bility of  evil,  should  the  certain  conditions  of  tempera- 
ture, nitration,  etc.  (which  oxidize  the  organic  matter)  be 
removed  or  fail  to  exert  their  influence. 

A  microscopic  examination,  both  of  the  water  and 
residue  on  evaporation,  is  often  employed  with  profit, 
and,  in  some  cases,  valuable  data  may  be  determined  from 
the  appearance  of  the  residue  after  evaporation  and  its 
odor  upon  ignition. 


SELECT  METHODS 


IN 


QUANTITATIVE  ANALYSIS, 


PART  II. 


USE  OF  PLATINUM  VESSELS. 

The  following  bodies  should  not  be  treated  in  plati- 
num vessels. 

1.  The  caustic  alkalies  as  well  as  baryta  and  strontia. 

2.  Fusible  metallic  sulphides,  or  mixtures  of  sulph- 
ides with  carbon;  especially  the  alkaline  sulphides. 

3.  Phosphates  and  carbon,  which  at  a  high  heat  form 
platinum  phosphide. 

4.  Metals  that  are  easily  fused,  or  metallic  oxides  that 
are  easily  reduced.    These  form  fusible  alloys  with  plati- 
num. 

5.  Chlorine,  and  all  mixtures  that  liberate  chlorine, 
either  in  the  cold  or  by  heat;  as  fusible  mixtures  of  a 
metallic  chloride  and  a  nitrate,  of  ammonium  sulphate 
and  a  chloride. 

Platinum  crucibles  may  be  cleaned  by  fusing  borax  or 
potassium  bisulphate  in  them,  and  dissolving  the  fused 
mass  with  boiling  water.  Sometimes  they  may  be  cleaned 
by  digesting  with  dilute  HC1.  To  brighten  them  scour 
with  sea-sand  and  water;  do  not  use  sharp  sand  or  emery. 


SELECT  METHODS  IN  QUANTITATIVE  ANALYSIS, 


LIMESTONE. 

For  technical  purposes,  it  is  sufficient  to  determine 
those  constituents  which  perform  the  active  part  in  any 
given  operation. 

The  more  common  constituents  of  limestone  may  be 
determined  as  follows: 

Pulverize  a  few  grms.,  dry  at  100°  C.  Weigh  1  grm.  of 
the  dry  sample,  transfer  it  to  a  porcelain  dish,  cover  with 
a  clock-glass,  add  20  c.  c.  of  water,  then  10  c.  c.  of  HC1, 
and  2  c.  c.  of  HNO3,  heat  till  effervescence  ceases,  then 
boil  and  filter.  (For  complete  separation  of  the  silica 
evaporate  to  dryness  on  the  water  bath.  When  perfectly 
dry,  cool,  moisten  with  HC1,  add  water  and  heat  until 
dissolved,  then  filter.*) 

Res.  (a)  =  Silica  and  silicates;  dry,  ignite  and  weigh; 
and  return  as  insoluble  matter.  If  it  is  desired  to  esti- 
mate the  elements  of  this  insoluble  matter,  mix  the 
ignited  residue  with  Ammonium  Fluoride,  cover  the  cru- 
cible and  ignite  till  fumes  cease  to  be  given  off,  repeat  this 
operation  till  constant  weight  is  obtained.  The  difference 
between  the  first  and  last  weight  is  the  silica.  Transfer 
the  residue  from  the  crucible  to  a  beaker  and  dissolve  in 
strong  HC1,  and  add  the  solution  to  filtrate  (a). 

Filt.  (a);  add  10  c.  c.  HC1,  then  ammonia  to  slight 
alkaline  reaction,  and  boil  till  excess  of  ammonia  is  ex- 
pelled, filter. 

Pp.  (6)  =  iron,  alumina,  and  phosphoric  acid.  If  this 
precipitate  is  small,  it  may  either  be  rejected  or  returned 

*  Classen  32. 


56  LIMESTONE. 

as  a  whole;  if  large,  separate,  and  estimate  the  per  cent, 
of  iron  and  alumina. 

Filt.  (6),  add  ammonium  oxalatein  excess,  (there  must 
be  sufficient  to  form  an  oxalate  of  all  the  magnesia  pres- 
ent), heat  just  to  boiling,  and  then  allow  it  to  stand  in  a 
warm  place  for  six  hours;  filter  by  decantation,  wash 
once  with  water  in  the  same  way;  now  dissolve  the  pre- 
cipitate in  dilute  HOI;  add  a  little  ammonium  oxalate, 
and  then  ammonia  in  excess;  boil,  filter  and  wash  by 
decantation.  The  re-precipitation  is  to  separate  the  mag- 
nesia which  is  precipitated  with  the  lime  in  the  first 
operation. 

Pp.  (c)  =  calcium  oxalate. 

Filt.  (c),  (The  united  filtrates);  concentrate  by  evap- 
oration, (adding  HC1  if  necessary,  to  prevent  the  forma- 
tion of  a  precipitate),  cool,  add  ammonia  in  excess,  then 
sodium  ammonium  phosphate,  and  allow  to  stand  six 
hours  in  a  cool  place;  filter  and  wash  with  water  con- 
taining ammonia. 

Pp.  (d)  =  Mg2(NH4)2(P04)2. 

ESTIMATION  OF  C02.* 

Fuse  2  grins,  of  vitrified  borax  in  a  platinum  crucible, 
cool  in  a  desiccator,  and  weigh;  add  about  0.5  grm.  of  the 
well  dried  limestone  and  weigh;  then  apply  heat  and 
gradually  increase  to  redness  and  continue  the  heat  till 
the  mass  is  in  a  state  of  quiet  fusion,  cool  and  weigh. 
The  loss  in  weight  is  the  CO2. 

Volumetric  Estimation  of  Calcium.t 

Weigh  1  grm.  and  dissolve  in  dilute  aqua  regia,  cool 
add  a  slight  excess  of  ammonia,  then  a  large  excess  of 
ammonium  oxalate;  heat  just  to  boiling  and  then  allow 
it  to  stand  till  the  precipitate  has  subsided;  filter  and  wash 
thoroughly  by  decantation,  till  the  ammonium  oxalate 

*  Fresenius  336. 
t  Sutton  133. 


IKON  QBE.  57 

has  been  removed.  Place  beneath  the  funnel  a  250  c.  c. 
flask,  pierce  the  filter,  wash  the  precipitate  into  the  flask, 
first  with  water,  then  with  dilute  sulphuric  acid  or  HC1; 
then  add  to  the  contents  of  the  flask  enough  dilute  sul- 
phuric acid  to  dissolve  (or  decompose)  the  calcium  oxalate, 
and  dilute  to  250  c.  c.  Titrate  portions  of  this  solution 
with  ^  KMnO4. 

The  T\  factor  of  CaO  =  .0028. 

Note.— If  there  is  much  magnesia  present,  the  calcium 
oxalate  should  be  dissolved  in  dilute  HC1  and  re-precipi- 
tated. 


IRON  ORE. 

Estimation  of  Iron,  Silica  and  Sulphur. 

Weigh  from  2  to  5  grms.  of  the  dry  ore,  mix  it  thor- 
oughly in  a  clock-glass  with  five  times  its  weight  of  the 
fusing  mixture.  Select  a  large  platinum  crucible,  and 
fuse  in  it  2  grms.  of  the  fusing  mixture,  when  well  fused 
lower  the  crucible  into  the  flame  of  the  Bunsen  burner  so 
that  the  bottom  becomes  cool  and  the  heat  is  upon  the 
sides;  remove  the  lamp,  introduce  into  the  crucible  one- 
third  of  the  ore  mixture,  cover  the  crucible  and  replace 
the  burner,  and  continue  the  heat  till  the  mass  has  become 
quiet;  now  introduce  another  third  and  treat  it  in  the 
same  way;  and  finally  the  last  third;  continue  the  heat 
till  the  mass  has  become  quiet,  then  apply  the  heat  to  the 
bottom  of  the  crucible,  and  finally  apply  the  heat  of  the 
blast-lamp  until  reduced  to  quiet  fusion.*  Sometimes  a 
semi-fused  mass  results  which  cannot  be  made  fluid  by 
the  strongest  heat.  Eemove  the  lamp  and  incline  the 
crucible  as  much  as  possible,  and  rotate  it  as  the  mass 
solidifies;  while  still  hot  plunge  it  side  wise  into  a  beaker 
of  cold  water,  remove  it,  and,  after  a  few  seconds  plunge 


*Fresenius383. 


58  IRON  QBE. 

again;  repeat  this  three  or  four  times.  Then  place  the 
crucible  on  its  side  in  the  beaker,  and  heat  till  the  mass 
separates,  remove  the  crucible,  and  continue  the  heat  till 
the  mass  is  disintegrated;  filter  and  wash  with  hot  water 
by  decantation. 

Res.  (a)  contains  the  iron,  alumina,  etc.  Dissolve  in 
HC1,  upon  a  water  bath ;  if  it  fails  to  dissolve,  filter  and 
re-fuse  the  insoluble  portion;  when  all  is  dissolved  except 
the  silica,  evaporate  to  dryness,  moisten  with  HC1  and 
take  up  with  water;  filter. 

Res.  (b)  =  part  of  the  silica. 

Filt.  (6),  dilute  to  a  given  number  of  c.  c.  and  esti- 
mate in  one  portion  the  iron  and  alumina  together,  and 
in  another  the  iron  by  titration. 

Note.— An  alcohol  lamp  should  be  used  if  possible  for 
the  fusion.  If  gas  is  used,  it  should  be  passed  through  a 
solution  of  potash  to  remove  the  sulphur  before  burning. 

Filt.  (a).  Add  HC1  cautiously  till  acid,  evaporate  to 
dryness,  heat  on  an  iron  plate  to  110°  C;  moisten  the  res- 
idue with  HC1,  add  water  and  boil;  filter. 

Res.  (c)  =  silica.  Dry  and  ignite  residues  (c)  and  (b) 
together. 

Filt.  (c).  Boil,  and  add  a  boiling  solution  of  barium 
chloride;  filter  after  standing  over  night,  and  determine 
the  sulphur  in  the  precipitate.  v 

Titration— of  the  iron  in  filt.  (b). 

Take  a  portion  of  the  filtrate,  add  HC1  till  strongly 
acid,  boil,  and  run  into  it  from  a  burette  stannous  chlo- 
ride, very  cautiously,  till  the  Fe2O3  is  reduced  to  FeO,  and 
the  SnCl2  is  in  slight  excess.  (When  the  reduction  is  com- 
plete the  solution  will  be  colorless);  now  add  5  c.  c.  of  a 
saturated  solutiod  of  HgCl2,  and  titrate  the  iron  with  & 
K2Cr2O7. 

For  the  estimation  of  manganese,  lime,  and  magnesia, 
dissolve  about  1  grm.  of  the  ore,  according  to  the  direc- 
tions given  below  for  the  estimation  of  phosphorus,  sep- 
.arate  the  iron  and  alumina  from  the  other  bases  as  basic 


IRON  QBE.  59 

acetates,*  and  the  manganese  with  bromine  or  ammonium 
sulphide.! 

Estimation  of  Phosphorus. 

Weigh  5  grms.  of  the  fine  dry  ore  and  digest  at  100°  C., 
with  strong  HC1,  till  all,  or  nearly  all  is  dissolved;  then 
boii  for  15  minutes,  filter  and  wash  slightly. 

Res.  (a).  Place  the  filter  with  its  residue  in  a  platinum 
crucible,  incinerate  thoroughly;  cool,  add  dry  jN"a2CO3  and 
fuse;  dissolve  in  dilute  HC1,  and  add  this  solution  with 
its  residual  silica  to  filtrate  (a). 

Filt.  (a).  Evaporate  to  dryness,  and  heat  on  an  iron 
plate  at  110°  C.,  till  it  no  longer  emits  an  odor  of  HC1;  cool 
slightly,  add  strong  HC1  and  boil  till  the  iron  is  dissolved ; 
evaporate  as  low  as  possible  without  formation  of  oxide 
of  iron,  then  add  30  c.  c.  of  HNO3  (1.42  sp.  gr.)  and  evap- 
orate to  a  sirupy  consistence,  then  add  more  HN03  and 
repeat  till  HC1  is  driven  off;  now  add  an  equal  volume  of 
water,  cool  and  filter. 

Filt.  (6).  Precipitate  the  phosphoric  acid  according 
to  directions  given  on  page  (60). 

Res.  (a)  and  Filt.  (a)  may  be  worked  separately  and 
if  no  phosphorus  is  found  in  res.  (a)  it  may  be  neglected 
in  the  analysis  of  ore  from  that  mine.  If  phosphorus  is 
found  in  res.  (a),  the  amount  may  be  determined  in  several 
samples  of  ore,  and  then  neglected  in  other  samples  from 
that  mine;  the  amount  thus  found  being  added  to  that 
obtained  from  filt.  (a),  in  all  subsequent  determinations. 

Estimation  of  Iron. 

Place  0.5  grms.J  of  the  very  fine  dry  ore  in  a  4  oz. 
.Erlenrneyer  flask,  add  15  c.  c.  of  strong  HC1,  mix  thor- 


*  Fresenius  429. 

t  Fresenius  430— 203.    Classen  73. 

\  Or,  better,  weigh  exactly  0.560  grms.  ore,  dissolve  in  15-20  c.  c. 
strong  HC1,  (in  a^small  beaker  which  has  no  lip  and  which  should  be 
closely  covered  with  a  watch-glass)  letting  substance  digest  for  some 


60  IKON  ORE. 

oughly,  place  the  flask  on  an  iron  plate  and  heat  at  from 
80°  to  90°  C.,  till  dissolved;  now  add  10  c.  c.  of  water  and 
run  in  stannous  chloride  solution,  one  drop  at  a  time, 
shaking  after  each  addition,  till  the  iron  solution  is 
colorless,  now  transfer  to  a  large  flask  and  dilute  to  about 
400  c.  c.  with  water,  then  add  10  c.  c.  of  a  saturated  solu- 
tion of  HgCl2,  which  should  produce  a  silky  white  pre- 
cipitate. Titrate  this  solution  with  •&  K2Cr2O7.  Or  add 
to  this  solution  10  c.  c.  of  a  cold  saturated  solution  of 
manganous  sulphate  and  titrate  with  ^  KMnO4;  the  end 
reaction  is  reached  when  the  pink  color  first  permeates 
the  whole  solution.  In  titrating  with  ft  KMnO4  it  is 
better  to  use  only  0.2  grms.  of  ore. 

Estimation  of  Sulphur. 

First  Method*  Place  1  grm.  of  the  fine  dry  ore  in  a 
porcelain  dish,  add  0.5  grms.  of  pulverized  KC103,  pour 
over  it  50  c.  c.  HNO3  (1.42  sp.  gr.)  and  cover  with  a  funnel 
or  clock-glass;  now  place  it  over  the  lamp  and  raise  the 
heat  gradually  and  bring  to  a  boil  and  boil  for  fifteen 
minutes,  adding  from  time  to  time  crystals  of  KC1O3; 
now  remove  the  cover  and  evaporate  to  a  small  bulk,  then 
add  strong  HC1  and  evaporate  to  dryness  on  a  water  bath.. 
Moisten  the  residue  with  strong  HC1,  add  water,  boil,  thf-n 
filter  and  wash  thoroughly;  nearly  neutralize  the  filtrate 
with  ammonia,  boil,  add  5  c.  c.  of  the  tartaric  acid  solu- 
tion, and  sufficient  BaCl2  solution  to  precipitate  the  sul- 
phur, boil,  then  allow  it  to  stand  all  night,  filter,  wash 
thoroughly  with  hot  water,  then  with  a  dilute  solution  of 
ammonium  acetate  to  dissolve  any  barium  nitrate  which 
may  adhere  to  the  sulphate. 

time  at  a  slight  heat  and  finishing  by  boiling.  To  the  hot,  concentrated 
solution  add  solution  of  SnCl2  to  exact  decolorization,  wash  into  a  400 
c.  c.  beaker,  add  15-30  c.  c.  of  solution  of  HgCl2,  dilute  largely  with  H2O 
and  titrate  with  ft  K2Cr2O7.  Each  c.  c.  of  K2Cr2O7  =  1  per  cent. 
(F.  C.  S.) 

*  Crooks  480. 


COAL.  61 

Second  Method.    Place  1  grm.  of  the  fine  dry  ore  in  a 

4  oz.  Erlenmeyer   flask,  moisten  thoroughly  with  the 
smallest  quantity  of  water  possible,  then  add  about  3  c.  c. 
of  bromine  and  shake  thoroughly;  now  heat  at  80°  C.,  for 

5  minutes,  then  add  15  c.  c.  of  strong  HC1  and  continue 
the  heat  15  minutes  longer,  transfer  to  a  porcelain  dish 
and  evaporate  to  dryness  on  a  water  bath,  etc.  (see  page 
52). 

Estimation  of  Manganese. 

Take  5  grms.  of  the  ore,  dissolve  in  strong  HC1,  cool, 
add  H2S04  in  slight  excess,  evaporate  till  HC1  is  all  ex- 
pelled, cool,  add  water,  heat  till  dissolved,  transfer  to  a 
500  c.  c.  flask;  dilute  largely,  add  zinc  oxide  in  excess, 
dilute  to  the  mark,  shake  thoroughly,  filter  off  a  portion 
through  a  ribbed  filter;  boil  a  measured  portion  of  this 
nitrate,  and  titrate  with  ^  KMnO4,  (see  page  70). 


COAL. 

Proximate  Analysis  of  Coal. 

Pulverize  a  sample  of  the  coal  in  a  rough,  porcelain 
mortar. 

Determination  of  Moisture.— Take  1  grm.  place  it  in  a 
covered  crucible,  and  heat  in  an  air  bath  at  115°  C.  for 
one 'hour,  cool  and  weigh.  Loss  =  Moisture. 

Determination  of  Volatile  Matter.— Take  1  grm.  of  the 
undried  coal,  place  it  in  a  platinum  crucible,  and  cover 
tightly;  heat  it  for  three  and  a  half  minutes  over  a  Bun- 
sen  burner,  and  then  without  cooling,  for  the  same  length 
of  time,  over  a  blast  lamp,  cool  and  weigh.  Loss,  less  the 
moisture  =  volatile  matter  and  one-half  of  the  sulphur 
present  as  sulphide  of  iron. 

Determination  of  Fixed  Carbon—  Incinerate  the  res- 
idue from  the  last  operation  until  the  carbon  is  burnt  off 


62  COAL. 

and  a  constant  weight  is  obtained.  Loss  —  fixed  carbon 
and  one-half  of  the  sulphur  present  as  sulphide  of  iron. 
The  last  weight  is  the  ash. 

Estimation  of  the  Total  Sulphur. 

Reagent.  Mix  thoroughly  4  grms.  of  calcined  magne- 
sia and  2  grms.  of  anhydrous  sodium  carbonate,  and  deter- 
mine the  sulphur  in  the  mixture.  Weigh  1  grm.  of  the 
very  fine  coal  and  mix  it  thoroughly  with  2  grms.  of  the 
reagent  in  a  porcelain  crucible,  which  should  not  be  more 
than  two-thirds  full.  Place  the  crucible  in  an  inclined 
position  on  a  triangle,  and  heat  very  gradually,  with  an 
alcohol  lamp,  increasing  the  heat  until  the  bottom  is  dull 
red.  (The  heat  must  not,  in  any  stage  of  the  operation, 
be  so  high  as  to  fuse  the  mass).  Stir  the  mixture  with  a 
platinum  wire  to  hasten  the  combustion,  which  requires 
about  one  hour.  When  the  carbon  is  all  oxidised,  remove 
the  lamp  and  allow  the  crucible  to  stand  until  perfectly 
cold,  then  add  1  gram  of  pulverized  ammonium  nitrate, 
mix  thoroughly  and  heat  for  5  or  10  minutes  at  a  red 
heat.  Cool,  dissolve  in  water  and  dilute  to  about  150  c.  c.; 
acidulate  with  HC1,  warm,  and  filter.  Boil  the  filtrate 
and  add  a  hot  solution  of  BaCl2;  allow  it  to  stand  one 
hour,  then  filter,  etc. 

Estimation  of  Sulphur,— present  as  calcium  sulphate. 

Take  4  grms.  of  the  coal,  add  6  grms.  sodium  carbo- 
nate (which  must  be  free  from  sulphur),  then  add  water 
and  boil  for  two  hours,  replacing  the  evaporated  water. 
Filter,  acidulate  the  filtrate  and  precipitate  the  sulphuric 
acid  in  the  usual  way. 

Phosphoric  Acid. 

If  present  in  the  coal,  it  will  be  found  in  the  ash,  and 
should  be  estimated  in  the  usual  manner. 


BLAST  FURNACE  SLAG.  63 

BLAST  FURNACE  SLAG. 

The  slag  may  contain— FeO,  Fe2O6,  FeS,  MnO,  A1203, 
CuO,  PbO,  ZnO,  CaO,  MgO,  K2O,  Na20,  SiO2,  TiO2,  SO3 
P2O5,  CaS. 

Scheme  for  Analysis. 

The  slag  when  not  soluble  in  HC1,  is  decomposed  by 
fusion.  (See  directions  for  fusing  iron  ore  for  the  estima- 
tion of  iron,  silica,  and  sulphur,  page  47). 

Res.  (a)  —  silica  and  titanic  acid.  (It  will  contain 
most  of  the  TiO2,  if  too  large  an  amount  of  HC1  has  not 
been  used  in  taking  up  the  residue.) 

Filt.  (a)  =  all  the  bases  acids  (also  some  Si02  and 
Ti02).  Reduce  the  ferric  to  ferrous  iron  by  sulphurous 
acid  and  then  pass  through  the  solution  H2S  gas,  and 
filter. 

Pp.  (6)  -  PbS,  CuS,  As2S3.  (If  there  is  any  arsenic  in 
the  slag,  it  will,  as  a  rule,  be  volatilized  in  preparing  the 
solution  and  will  not  appear  at  this  point).  The  copper 
and  lead  can  best  be  separated  by  sulphuric  acid  and 
alcohol. 

Filt.  (6).  Add  HC1,  boil,  then  add  a  few  crystals  of 
KC103  and  continue  the  boiling  until  the  odor  of  Cl  has 
disappeared;  now  dilute  the  solution  to  600  or  800  c.  c. 
and  precipitate  the  iron  and  alumina  as  basic  acetates 
and  filter. 

Pp.  (c)  =  Fe203,  A12O3,  SiO2  Ti02,  P2O5.  Pierce  the 
filter  and  wash  the  precipitate  into  a  beaker,  and  dissolve 
in  sulphuric  acid;  nearly  neutralize  with  ^H4OH,  dilute 
if  necessary,  pass  H2S  gas  till  the  Fe,O3  is  reduced  to  FeO, 
boil  for  some  time,  replacing  the  evaporated  water;  filter. 

Pp.  (d)  =  Si02,  TiO2.  Add  this  prcipitate  to  residue 
(a). 

Filt.  (d).  Add  HNO3,  and  boil  till  the  iron  is  oxidized,, 
filter  if  necessary,  dilute  to  a  given  number  of  c.  c.  and 
estimate  the  iron  and  alumina  in  one  portion,  and  the 
iron  in  another  portion  by  titration. 


64  BLAST  FUBNACE  SLAG. 

Fill.  (c).  Concentrate  to  200  c.  c.  Add  acetic  acid  and 
pass  H2S  gas;  filter. 

Pp.  (e)  =  ZnS.  Dissolve  in  HC1;  filter  out  the  sulphur, 
and  precipitate  the  zinc  with  sodium  bi-carbonate  in  a 
porcelain  dish. 

Filt.  (e).  Concentrate  to  200  c.  c.  by  boiling,  filter  if 
necessary  and  precipitate  the  manganese  with  bromine, 

Pp.  (/)  =  manganese. 

Filt.  (/).  Add  ammonia  till  alkaline,  boil  and  add 
ammonium  oxalate,  filter. 

Pp.  (g)  =  CaC804. 

Filt.  (</)  =  MgO,  precipitate  with  sodium  ammonium 
phosphate. 

Res.  (a)  -f  Pp.  (d);  dry,  ignite  and  weigh;  treat  the 
ignited  residue  with  ammonium  fluoride,  and  weigh  the 
residual  Ti08;  or  separate  the  SiO2  and  Ti02  by  fusing 
with  fused  KHSO4. 

Estimation  of  Phosphoric  Acid  and  Sulphur. — See 
directions  for  estimating  these  in  iron  ore. 

Estimation  of  Silica. 

Slags  which  have  been  cooled  slowly  can  only  be  par- 
tially dissolved  by  acids.  To  obtain  a  sample  which  will 
be  decomposed  by  HC1,  the  following  method  has  been 
adopted. 

A  cast-iron  pan,  similar  to  an  assay-pan,  5  inches 
square,  and  having  in  it  four  shallow,  hemispherical  cups, 
is  riveted  to  a  handle  20  inches  long.  The  cups  have  the 
furnace-numbers  countersunk  in  the  bottoms.  The  sam- 
ple is  taken  by  filling  this  pan  directly,  or  by  means  of  a 
ladle,  with  the  fluid-cinder  as  it  flows  from  the  cinder- 
notch.  It  chills  instantly,  and  by  the  time  it  can  be  car- 
ried to  the  laboratory,  is  ready  for  treatment.  By  this 
system,  there  is  no  danger  of  confusion,  and  there  are 
four  small  cakes  from  which  to  choose  a  final  sample. 

Take  from  0.2  to  0.5  grms.  in  a  porcelain  dish,  add 
strong  HC1,  heat  on  a  water  bath  and  stir  thoroughly 


IKON  AND  STEEL.  65 

with  a  platinum  wire;  when  thoroughly  mixed,  transfer 
to  an  iron  plate  and  evaporate  to  dryness,  cool,  add  15  c.  c. 
of  HC1  (1.12  sp.  gr.),  and  boil  2  or  3  minutes  to  dissolve 
titanic  acid,  then  add  an  equal  volume  of  water  and  filter. 

Res.  (a)  =  SiO2. 

Filt.  (a)  can  be  used  for  estimating  A12O3,  MgO  and 
CaO. 


IRON  AND  STEEL. 

Estimation  of  Phosphorus. 

Take,  for  analysis,  of  Bessemer  or  other  low-carbon 
steels,  from  3  to  5  grammes;  of  crucible  steel,  10  gramm.es; 
of  pig-iron,  1  to  5  grammes,  according  to  the  percentage 
of  phosphorus  supposed  to  be  present.  Of  iron,  high  in 
phosphorus  (1  per  cent.),  take  1  gramme. 

Place  in  a  No.  4  evaporating  dish  the  amount  of  iron 
or  steel  decided  upon,  cover  with  a  funnel  which  will  just 
fit  inside  the  dish,  and  then  add  gradually  HK03  (1.20 
specific  gravity),  using  12  c.  c.  of  acid  for  each  gramme  of 
steel  or  iron  taken.  (A  larger  quantity  of  acid  will  be 
required  for  small  samples.)  When  the  full  amount  of 
acid  has  been  added,  and  the  violent  action  has  ceased, 
place  the  evaporating  dish  on  a  sand-bath,  add  10  c.  c. 
HNO3  (1.40  specific  gravity),  and  boil  till  the  bulk  of  the 
solution  is  reduced  about  one-half.  Then  add  10  c.  c. 
HN03  (1.40  specific  gravity),  continue  the  boiling,  and  add 
from  time  to  time,  during  the  next  15  minutes,  small  por- 
tions of  pulverized  KC103  till  about  2  grammes  has  been 
added.  (If  the  solution  shows  signs  of  going  dry,  more 
strong  acid  must  be  added.)  This  will  precipitate  the 
manganese,  with  some  iron.  Sometimes  it  happens  that 
the  manganese  does  not  come  down  readily  and  more 
KC1O3  or  further  concentration,  or  both,  will  be  required. 

The  process  is  not  complete  till  the  manganese  is 
precipitated,  which  may  be  known  by  the  appearance 
6 


66  IRON  AND  STEEL. 

of  a  dark,  mirror-like  deposit  on  the  dish,  at  the  edge 
of  the  solution. 

Boil  the  solution  5  minutes  after  the  last  addition  of 
KC1O3,  then  add  cautiously  (to  prevent  sudden  explo- 
sions) strong  HC1  till  the  manganese  and  iron  are  dis- 
solved. (From  2  to  5  c.  c.  will  be  sufficient,  do  not  use 
more  than  5  c.  c.  but  less  if  possible.) 

Continue  the  boiling  till  the  chlorine  is  all  expelled, 
adding  from  time  to  time  HNO3  (1.40  specific  gravity)  to 
prevent  the  solution  from  evaporating  to  dryness. 

Now,  add  an  equal  bulk  of  water  to  the  solution,  and 
boil  from  5  to  10  minutes,  cool,  and  filter  into  a  flask. 
This  filtration  may  be  omitted,  if,  as  is  generally  the  case 
with  low-silicon  steels,  there  is  no  residue. 

(X).  Place  the  flask  under  the  hydrant,  till  the  solu- 
tion is  perfectly  cold;  then  add  gradually  strong  ammonia, 
with  constant  stirring,  till  the  solution  is  changed  into  a 
pasty  mass,  and  the  ammonia  is  in  slight  excess;  now 
add  cautiously  EOs  O3  (1.40  sp.  gravity)  till  the  mass  is 
dissolved;  cool  the  solution  to  60°  C.,  it  should  then  have 
a  straw  color.  If  the  solution  has  a  decided  red  tinge, 
iron  will  be  thrown  down  with  the  phospho-molybdate 
precipitate,  which  can  only  be  removed  by  re-precipita- 
tion, and  with  a  loss  of  phosphorus. 

The  red  tinge  can,  as  a  rule,  be  removed  by  adding 
some  strong  HNO3,  shaking  well,  and  then  adding  about 
25  c.  c.  of  water.  (The  solution  should  now  not  exceed 
200  c.  c.)  Heat  to  60°  C.,  and  add  60  c.  c.  of  molybdate 
solution,  cork  the  flask  and  shake  violently  for  five  min- 
utes; place  the  flask  on  an  iron  plate,  heated  to  60°  C.  (not 
more),  and  let  it  stand  till  the  precipitate  subsides. 

By  cooling  the  solution,  before  adding  the  molybdate 
solution,  and  not  raising  the  heat  above  60°  C.,  the  phos- 
pho-molybdate precipitate  is  obtained  free  from  molybdic 
acid,  and  also,  (if  the  above  precautions  have  been  ob- 
served), from  iron ;  and  will  contain  only  a  part  of  the 
silica,  the  whole  of  the  silica  being  thrown  down  only  by 
high  heat  and  long  standing.  Filter  through  a  four  inch 


IRON  AND  STEEL.  67 

filter  and  wash  the  precipitate  (keeping  as  much  of  it  in 
the  flask  as  possible)  with  the  acid  solution  of  ammonium 
nitrate  or  with  tTNO3  diluted  with  fifty  times  its  bulk  of 
water;  wash  till  the  wash-water  will  not  give  a  red  color 
with  potassium  thiocyanate. 

Place  the  flask,  which  contains  the  bulk  of  the  precip- 
itate, under  the  funnel,  and  dissolve  the  precipitate  of 
phospho-molybdate  on  the  filter  with  a  3  per  cent,  solution 
of  ammonia.  The  filter  should  remain  perfectly  white,  or 
only  slightly  tinged  with  red  on  the  upper  edge.  If  much 
colored  with  iron,  run  through  the  filter  into  the  ammo- 
niacal  solution  enough  dilute  nitric  acid  to  dissolve  this 
oxide  of  iron,  and  render  the  solution  slightly  acid;  then< 
add  5  c.  c.  molybdate  solution,  heat  the  flask  to  80°  C.,  let 
it  stand  15  minutes  or  till  the  precipitate  subsides;  filter 
and  wash  as  before.  This  will  give  a  phospho-molybdate 
precipitate  free  from  iron.  Dissolve  this  precipitate  with 
a  3  per  cent,  solution  of  ammonia,  as  above. 

To  the  ammoniacal  solution  of  phospho  molydate  add 
5  c.  c.  strong  HC1,  or  enough  to  render  the  solution  de- 
cidedly acid;  dissolve  the  precipitate  thus  formed  wiih 
ammonia,  adding  it  gradually,  so  that  the  last  drop  will 
just  disperse  the  yellow  color,  leaving  the  solution  cloudy 
and  with  a  peculiar  sweet  smell.  Boil  the  solution  10 
minutes;  then  set  it  aside  till  the  silica  becomes  floccu- 
lent  (about  10  minutes);  remove  the  separated  silica  by 
filtering  through  a  small,  close  filter — or  better,  through' 
the  filter  from  which  the  phospho-molybdate  precipitate 
has  been  dissolved,  for  the  silica  is  not  so  liable  to  pass 
through  that,  as  through  a  new  filter. 

By  repeated  tests  I  have  been  unable  to  find  phos- 
phorus in  the  separated  silica  when  iron  was  not  present,, 
but  have  always  found  it  when  the  silica  contained  iron.. 
To  the  filtrate  add  5  c.c.  of  ammonia;  cool;  and  then  add 
gradually  15  c.  c.  of  magnesia  mixture,  keeping  the  solu- 
tion in  constant  motion ;  cork  the  flask  and  shake  vio- 
lently for  two  or  three  minutes;  set  it  aside  for  three 
hours;  filter  and  wash  with  ammonia  water  (3  parts  of 


€8  IKON  AND  STEEL. 

water,  1  part  of  ammonia)  till  the  wash-water,  acidulated 
with  nitric  acid,  gives  no  precipitate  with  silver  nitrate. 
Place  the  moist  filter  with  its  precipitate  in  a  plati- 
num crucible;  cover,  and  apply  a  strong  heat  till  the  filter 
is  thoroughly  charred;  remove  the  cover;  turn  the  cruci- 
ble on  its  side,  and  ignite  till  the  filter  is  white:  then 
place  the  crucible  in  the  upright  position;  cover,  and  heat 
five  minutes  with  the  blast.  This  will  volatilize  the 
greater  part  of  the  molybdic  acid,  which  is  nearly  always 
present  with  the  ammonio-magnesium  phosphate.  The 
determination  may  be  made  in  six  hours. 

Result  =  Mg2P207.    27.93#  =  P. 

Nitric  Acid  Process. 

Take  a  weighed  sample  of  the  steel,  and  dissolve  in 
HNO3  (1.20  sp.  gr.);  add  5  c.  c.  of  HC1,  evaporate  to  dry- 
ness  and  heat  on  an  iron  plate  to  120°  C.  until  all  of  the 
acid  is  removed;  cool,  add  strong  HC1  and  heat  till  dis- 
solved, and  evaporate  cautiously  to  about  15  c.  c.,  now  add 
40  c.  c.  strong  HN03  and  boil  down  to  15  c.  c.:  now  move 
the  dish  about  so  as  to  moisten  any  dry  scales  that  may 
have  formed,  when  partially  cold  add  40  c.  c.  of  water 
(this  should  give  a  clear  solution)  filter  and  wash.  The 
filtrate  should  not  exceed  150  c.  c. 

The  rest  of  the  operation  is  conducted  as  described  on 
page  66  commencing  at  (X). 

E.  FRED.  WOOD'S  DIRECT  PROCESS.* 

Method  A.    Applicable  to  iron  and  steel  and  manga- 
nese-iron alloys. 

Weigh  1.63  grm.  material  into  a  4-inch  evaporating 
dish,  add  35  c.  c.  1.20  HNO3.  Cover  with  a  watch  glass, 
when  violent  action  has  ceased  put  over  a  lamp  and  boil 
down  till  nearly  or  quite  dry,  remove  from  lamp,  and  add 
15-20  c.  c.  concentrated  HC1,  again  boil  down  to  dryness, 
and  heat  to  200°  C.  for  one  hour,  or  until  there  is  no  longer 

*  Jour.  Analyt.  Chem.  Vol.  I,  p.  138. 


IRON  AND  STEEL.  69 

any  smell  of  acid,  remove  from  lamp,  cool,  add  30-35  c.  c. 
concentrated  HC1,  boil  till  all  is  dissolved  except  silica 
and  graphite,  dilute  with  a  little  hot  water,  filter  into  200 
c.  c.  beaker,  washing  filter  with  HC1  and  hot  water.  (The 
filtrate  and  washings  need  not  exceed  125  c.  c.)  Boil 
down  to  15  c.  c.,  add  35-40  c.  c.  HNO3,  (sp.  gr.  1.42),  again 
boil  down  to  15  c.  c.,  add  5  c.  c.  water,  cool,  add  70  c.  c. 
molybdic  acid  solution,  stir  well,  let  stand  at  a  tempera- 
ture of  20°  to  30°  C.  for  2  hours,,  or  until  the  yellow  pre- 
cipitate is  completely  settled  and  solution  is  perfectly 
clear.  Prepare  a  weighed  filter  by  drying  a  6  or  7  cm. 
filter  of  Munktell's  JSo.  1  Swedish  paper  for  35  minutes 
in  steam  drying  bath  at  100°  C.,  weigh  rapidly  to  within 
1  milligram.  Remove  most  of  supernatant  liquor  with  a 
siphon,  filter  remainder,  and  wash  precipitate  on  a  filter 
with  water  containing  2  per  cent,  of  1.20  nitric  acid;  wash 
precipitate  and  filter  4  to  6  times  with  this  mixture,  dry 
at  100°  C.  for  45  minutes  (longer  if  precipitate  is  very 
heavy,  the  point  of  the  filter  should  be  blue  when  dried 
enough)  weigh.  The  yellow  phospho-molybdate  of  am- 
monia contains  1.63  per  cent,  phosphorus,  so  that  each 
milligram  =  .001  per  cent,  phosphorus  in  sample. 

Method-  B.    Applicable  to  steel  and  wrought  iron. 

Weigh  1.63  gm.  steel  into  200  c.  c.  beaker,  add  35  c.  c. 
1.20  HN03  and  cover  with  watch  glass,  when  violent 
action  has  ceased,  place  over  lamp  and  boil  till  carbonace- 
ous matter  is  dissolved  and  solution  is  concentrated  to  15 
c.  c.,  add  15  to  20  c.  c.  chromic  acid  solution,  boil  down  to 
15  c.  c.,  add  5  c.  c.  water,  cool,  precipitate  and  weigh  as  in 
method  A.  For  very  rapid  work  nearly  as  accurate  re- 
sults can  be  obtained  in  one  hour.  When  solution  is 
concentrated  after  adding  chromic  acid  solution,  rince 
into  Erlenmeyer  flask  using  as  little  water  as  possible 
(not  over  8  c.  c.),  cool  to  30°  C.,  add  70  c.  c.  molybdic  acid 
solution,  previously  warmed  to  30°  C.,  cork  and  shake 
violently  for  five  minutes,  let  stand  10  minutes,  when 
precipitation  will  be  complete.  Filter  through  weighed. 


70  IEON  AND  STEEL. 

filter,  wash,  dry  15  minutes  at  135°  C.  This  method  was 
tried  in  pig  iron,  but  the  concentrated  HN03  precipitated 
silica  in  such  a  form  that  it  could  not  be  filtered.  This 
difficulty  was  avoided  in 

Method  C.    Applicable  to  pig  irons. 

Place  1.63  gm.  in  a  200  c.  c.  beaker,  add  35  c.  c.  1.20 
HNOg,  boil  3  or  4  minutes,  add  3  to  5  drops  hydrofluoric 
acid  and  15  c.  c.  water,  boil  down  to  15  c.  c.,  add  18  c.  c. 
chromic  acid  solution,  boil  5  minutes.  Filter  through 
asbestos  filter,  wash  filter  with  hot  water,  concentrate 
filtrate  to  20  c.  c.,  cool  and  precipitate.  Time  required 
about  2%  hours.  As  yet  satisfactory  results  have  not 
been  obtained  on  ferromanganese,  though  the  method 
works  well  on  white  iron  and  spiegel  up  to  20  per  cent, 
manganese. 

SPECIAL  REAGENTS. 

Chromic  Acid  Solution. — Dissolve  about  50  gins.  Cr03 
in  1  liter  1.42  nitric  acid,  by  warming.  The  solution 
should  be  renewed  occasionally  as  it  seems  to  lose  oxydiz- 
ing  power  on  standing  3  or  4  weeks. 

Filter  Paper. — The  best  paper  for  filtering  off  silica 
and  graphite  in  method  A  was  found  to  be  Schleicher  and 
Schiill's  £To.  597,  about  9  cm.  diameter  filter  being  used. 
For  collecting  and  weighing  the  phospho-molybdate  the 
most  suitable  paper  found  was  J.  C.  Munktell's  ]STo.  1 
Swedish. 

Volumetric  Method  of  Estimating 
Phosphorus. 

The  accuracy  of  this  method  will  depend  upon  the 
composition  of  the  phosphomolybdate  precipitate  being 
constant.  To  test  this,  I  have  made  many  estimations; 
and  the  precipitates  obtained  from  known  quantities  of 
phosphorus  agreed  with  each  other,  and  corresponded 
with  the  following  well  known  formula  when  the  pre- 
cipitation took  place  at  60°  C.  or  less. 

0.    P2O5.    22MoO3.    12H2O. 


IKON  AND  STEEL.  71 

This  formula  contains  1.6838  per  cent,  of  phosphorus, 
and  86.04  per  cent.  MoO3. 

The  volumetric  method  is  based  upon  the  fact,  that, 
the  MoO3  in  the  phosphomolybdate  precipitate  can  be 
reduced  to  Mo2O3  by  zinc  and  dilute  sulphuric  acid;  and 
the  Mo203  thus  formed  can  be  oxidized  to  MoO3  by  titrat- 
ing the  solution  with  potassium  permanganate.  The  fol- 
lowing reaction  takes  place  in  this  titration:  5Mo2O3 + 
6KMnO4  +  9H2SO4  =  10MoO3  +  3K2SO4  -f  6MnSO4  + 
9H2O.  From  this  reaction  we  obtain  the  T\  factor  of 
MoO3,  as  follows : 

6KMnO4  oxidizes  5Mo2O3  to  10  Mo03 

Therefore,  KMnO4  =  -V°-  MoO3;  or  by  substituting  the 
atomic  weights,  158  =  240.;  and  by  dividing  by  5  we  have 
31.6  =  48. 

ft  factor  of  KMnO,  =  .00316 

&      "        "  Mo03      =  .0048 

From  the  foregoing  data,  we  obtain  the  ft  factor  of 
phosphorus  by  this  simple  proportion: 

86.04  (MoO3)  :  1.6838  (P)  :  :  0.0048  (ft  factor  of  Mo03)  :  x 
=  0.0000939  (ft  factor  of  P)  or  0.000094. 

This  factor,  thus  obtained  by  calculation,  has  been 
verified  by  analysis. 

The  first  results  obtained  were  not  constant,  and  were 
too  high,  due  to  the  varying  amounts  of  zinc  sulphate 
present,  which  is  formed  in  reducing  the  MoO3;  for  I 
have  found  that  pure  zinc  sulphate  as  well  as  that  formed 
in  reducing  the  MoO3  to  Mo2O3,  will  reduce  potassium 
permanganate.  It  is  therefore  necessary  to  first  ascertain 
the  reducing  power  of  the  zinc  sulphate  which  is  formed 
in  the  first  part  of  this  operation,  wrhich  may  be  determ- 
ined as  follows: 

Take  10  grms.  of  Zn,  add  75  c.  c.  of  water  then  15  c.  c. 
of  strong  H2S04,  when  violent  action  has  ceased,  heat  so 
as  to  maintain  a  rapid  evolution  of  hydrogen  during  15 
minutes,  filter,  to  the  filtrate  add  2  c.  c.  of  H2SO4,  cool 


72  IEON  AND  STEEL. 

under  the  hydrant  to  30°  or  40°  C.,  and  titrate  with  -ft 
KMn04  to  a  permanent  pink  color.  Deduct  the  c.  c.  of 
KMnO4  used  from  each  titration  of  the  phosphomolyb- 
date  precipitate.  (This  reducing  power  of  zinc  sul- 
phate varies  with  the  zinc  used,  but  is  constant  for  the 
same  zinc). 

Reduction  and  Titration  of  the  Phosphomolybdate 
Precipitate.— After  washing  the  precipitate  in  the  usual 
manner,  it  must  be  washed  twice  with  pure  water  to  re- 
move the  nitric  acid ;  then  dissolve  in  dilute  ammonia, 
and  dilute  the  solution  to  150  c.  c.  with  water,  divide  into 
two  equal  portions  and  to  each  add  10  grms.  of  the  tested 
Zn  and  15  c.  c.  of  strong  H2SO4,  cover,  and  apply  heat  to 
maintain  a  rapid  evolution  of  hydrogen  for  15  minutes, 
now  filter  as  rapidly  as  possible  allowing  the  undissolved 
zinc  to  go  on  to  the  filter,  rinse  out  the  flasks  several 
times  with  dilute  H2SO4,  then  fill  the  filters  once  with 
cold  water,  and  as  soon  as  this  has  passed  through,  cool 
the  solutions  under  the  hydrant  and  titrate  each  as 
rapidly  as  possible  with  •&  KMnO4  till  a  faint,  permanent, 
pink  color  is  produced.  The  solution  after  reduction  is 
dark,  which  on  titration  grows  lighter  till  it  becomes  per- 
fectly white,  then  a  few  more  drops  of  KMnO4  will  pro- 
duce the  pink  color. 

Estimation  of  Silicon. 

Dissolve  0.5  grm.  in  20  c.  c.  of  dilute  sulphuric  acid  ( 1 
pt.  H2SO4  to  8  pts.  water)  in  a  porcelain  evaporating  dish 
When  dissolved  add  1  c.  c.  of  HNO3  ( 1.40  sp.  gr.),  and  2 
c.  c.  of  strong  H2S04  and  evaporate  until  white  fumes  of 
S03  are  given  off,  continue  the  heat  5  or  10  minutes;  then 
cool,  add  some  strong  HC1,  then  10  c.  c.  of  water,  and  heat 
until  dissolved;  filter,  wash  with  hot  water  containing  5 
per  cent  .of  HNO3.  Residue  =  Si02. 

In  estimating  silicon  in  ferro-manganese  and  spiegel, 
it  is  necessary  to  dissolve  in  HNO3  ( 1.40  sp.  gr.),  then  add 
H2S04  and  proceed  as  above. 


IKON  AND  STEEL.  73- 

Estimation  of  Sulphur. 

First  Method. 

Take  from  3  to  5  grms.,  place  in  a  generating  flask,- 
which  has  a  funnel-tube  with  a  stop-cock,  connect  the 
flask  with  three  small,  three-bulb  U-tubes;  fill  these  tubes 
one-third  full  with  a  solution  of  KMn04  ( 1  grm.  KMnO* 
to  200  c.  c.  water).  The  KMnO4  must  be  free  from  sul- 
phuric acid.  Now,  gradually  let  into  the  generating  flask 
dilute  HC1  ( 1  pt.  HC1  to  2  pts.  water ).  The  HC1  must  be 
free  from  Cl.  A  rapid  evolution  of  gas  must  be  avoided. 
Continue  the  operation  until  all  of  the  iron  is  dissolved, 
then  heat  the  flask  nearly  to  boiling,  and  draw  air 
through  for  some  time.  Empty  the  U-tubes  into  a  beaker, 
rinse  first  with  water,  then  with  strong  HC1  to  dissolve- 
the  oxide  of  manganese  adhering  to  the  sides.  Now  add 
about  15  c.  c.  of  strong  HC1  and  evaporate  rapidly;  after 
the  solution  has  been  reduced  to  about  one  half  of  its 
original  bulk,  if  it  is  not  clear  add  more  HC1  and  con- 
tinue the  boiling  until  a  clear  solution  is  obtained;  that 
is  until  the  KMnO4  has  all  been  reduced.  Neutralize  the 
excess  of  HC1  with  ammonia  and  precipitate  the  sul- 
phuric acid  in  the  usual  manner. 

If  this  last  solution  contains  a  sediment,  on  account, 
of  impurities  in  the  KMn04,  then  filter  before  precipita- 
tion. 

If  the  whole  amount  of  sulphur  is  to  be  saved,  then, 
the  residue  in  the  generating  flask  must  be  filtered  out, 
digested  with  aqua  regia  twice,  and  evaporated  to  dry- 
ness  each  time,  then  taken  up  with  HC1  and  water,  filtered, 
and  the  filtrate  added  to  the  above  solution  before  pre- 
cipitation with  BaCl2. 

Second  Method. 

Proceed  according  to  directions  given  above,  using 
in  the  U-tubes  in  place  of  KMnO4,  a  solution  of  caus- 
tic soda  (1  pt.  NaHO  to  5  pts.  water).  This  solution 
of  soda  must  be  free  from  sulphur,  or  its  compounds,  or- 


74  IRON  AND  STEEL. 

any  agent  which  will  reduce  iodine.    Empty  the  U-tubes 
into  a  large  flask,  rinse  well  with  water,  and  dilute  to  200 
or  300  c.  c.,  acidify  with  strong  HC1  ( free  from  Cl ),  add 
starch  solution,  and  titrate  with  T^  solution  of  iodine. 
T&T  factor  of  S  -  .00016. 

Third  Method. 

Cadmium  Solution.  Take  250  grms.  of  CdCl,  dissolve 
it  in  water,  and  add  enough  NH4OH  to  dissolve  the  pre- 
cipitate which  may  form,  then  heat  and  filter,  if  neces- 
sary, and  dilute  to  four  litres  with  strong  NH4OH. 

Take  15  c.  c.  of  this  solution,  dilute  it  with  150  c.  c.  of 
water,  if  a  precipitate  forms  add  some  NH4OH  to  dissolve 
it.  JSTow  take  5  grms  of  iron  in  a  generating  flask  and 
dissolve  it  with  dilute  HC1  (1  of  acid  to  2  of  water)  and 
pass  the  gas  into  this  last  solution  of  CdCl.  When  the 
iron  is  all  dissolved,  dilute  the  cadmium  solution  with 
water  to  400  c.  c.  then  add  gradually  dilute  HC1  till  the 
solution  is  acid;  now  titrate  with  standard  iodine. 

The  sulphur  in  the  residue  may  be  estimated  as 
directed  in  the  first  method. 

If  perfectly  accurate  results  are  desired  the  cadmium 
sulphide  must  be  filtered  off  and  then  removed  from  the 
filter  and  titrated;  for  the  cadmium  solution  which  de- 
stroys iodine,  absorbs  carburetted-hydrogen,  thus  giving 
too  high  a  per  cent  of  sulphur. 

Estimation  of  Manganese. 

GENERAL   METHOD    FOR    PRECIPITATING    THE   MAN- 
GANESE AS  MnO2  BY  HX03  AND  KC103. 

Take  of  pig-iron  from  2  to  5  grms.,  dissolve  in  HX03 
(1.2  sp.  gr.),  using  12  c.  c.  of  the  acid  for  each  grm.  of  iron 
taken,  filter,  evaporate  the  filtrate  to  a  pasty  condition, 
and  then  add  40  c.  c.  HNO3,  (1.40  sp.  gr.).  Take  of  steel  2 
grms.,  dissolve  in  25  c.  c.  of  HN03  (1.20  sp.  gr.)  and  evapo- 
rate to  a  pasty  condition,  then  add  40  c.  c.  of  HX03  (1.40 


IRON  AND  STEEL.  75 

sp.  gr.).  Take  of  spiegel  0.5  grm.,  or  of  ferro  0.1  grin.,  dis- 
solve in  40  c.  c.  of  HN03  (1.40  sp.  gr.). 

Use  a  pint  beaker  for  dissolving  the  iron  or  steel,  and 
a  12  oz.  beaker  for  spiegel  or  ferro. 

Boil  the  solution  thus  prepared,  and  while  boiling  add 
2  grms.of  pulverized  KC103,in  small  quantities  at  a  time; 
this  need  not  take  more  than  five  minutes. 

Now  add  20  c.  c.  of  HNO3  (1.40  sp.  gr.),  boil  and  add  a 
little  more  KC1O3  (about  0.1  grm.),  boil  5  minutes  after  the 
last  portion  of  KC103  has  been  added,  then  remove  from 
the  lamp  and  cool.  Filter  through  purified  asbestos,  suck 
the  filter  dry  with  the  aspirator,  then  wash  with  purified 
HNO3  (1.40  sp.  gr.)  until  the  acid  comes  through  clear, 
again  suck  dry  with  the  aspirator. 

Pp  (a)  =  Mn02  +  Fe2O3  with  some  nitric  acid. 

GRAVIMETRIC  METHOD. 

Transfer  Pp  (a)  with  the  asbestos  to  the  beaker  in 
which  the  precipitate  was  formed,  add  HC1  and  boil  until 
the  MnO2  is  all  dissolved;  filter  and  wash  with  hot  water. 
The  filtrate  contains  some  iron  with  the  manganese; 
nearly  neutralize  with  ammonia,  add  a  very  small  lump 
of  sodium  acetate,  and  boil;  filter,  wash  slightly  with  hot 
water,  redissolve  the  precipitate  in  HC1,  and  reprecipitate 
the  iron;  unite  the  two  filtrates,  heat  nearly  to  boiling, 
add  an  excess  of  sodium  ammonium  phosphate,  then  am- 
monia in  slight  excess  and  boil  till  the  precipitate  presents 
a  silky  appearance.  Filter,  dry,  ignite  and  weigh. 

Eesult  =  Mn2P2O7.  Wt.  of  Mn2P207  X  .3873  =  Wt. 
of  Mn. 

VOLUMETRIC  METHOD. 

No.l. 

Transfer  Pp  (a)  with  the  asbestos  to  the  beaker  in 
which  the  precipitate  was  formed,  add  about  75  c.  c.  of 
water  and  then  run  in  T^  ammonio-ferrous  sulphate 
(made  by  dissolving  39.2  grms.  of  the  salt  in  water,  adding 
50  c.  c.  of  strong  H2SO4  and  diluting  to  one  litre,  when 


76  IRON  AND  STEEL. 

cold),  5  c.  c.  at  a  time,  sfirring  thoroughly  after  each  ad- 
dition, until  the  MnO2  is  all  dissolved.  (Do  not  heat).  A 
weighed  amount  of  the  salt  and  H2SO4  may  be  added  in- 
stead of  the  ft  solution.  Now  titrate  back  the  excess  of 
ammonio-ferrous  sulphate  with  TN^  KMnO4,  the  first  Hash 
of  the  rose  color  is  the  end  reaction;  deduct  from  the 
KMnO4  used  0.2  c.  c.  If  in  doubt  about  the  end  reaction, 
place  a  few  drops  of  freshly  prepared  ferricyanide  of  po- 
tassium on  a  porcelain  plate,  and  test  the  solution  with 
it,  titrating  back  and  forth  with  ft  ammonio-ferrous 
sulphate,  and  ft  KMn04,  until  a  satisfactory  end  reaction 
is  obtained. 

Multiply  the  number  of  c.  c.  of  ft  ammonio-ferrous- 
sulphate  actually  used  by  .00275  the  ft  factor  of  Mn. 

VOLHARD'S  VOLUMETRIC  PROCESS. 

No.  2. 

This  process  is  based  upon  the  following  reaction 
which  takes  place  in  titrating  manganous  sulphate  with 
potassium  permanganate. 


ft  factor  of  Mn  =  .00165. 

Take  2  grms.  of  steel  (more  or  less  according  to  the 
per  cent,  of  Mn),  place  it  in  a  porcelain  dish,  add  10  c.  c. 
of  strong  H2SO4,  and  40  c.  c.  of  HNO3  (1.20  sp.  gr.);  when 
dissolved  boil  on  a  sand  bath  until  white  fumes  of  SO3 
are  given  off,  continue  the  boiling  two  minutes  longer. 
Cool,  dissolve  in  hot  water,  transfer  to  a  large  flask  grad- 
uated to  hold  500  c.  c.,  (  The  dilution  must  be  250  c.  c.  for 
each  grm.  of  iron  taken  )  add  dry  sodium  carbonate  till 
the  solution  turns  red,  then  add  an  excess  of  the  oxide  of 
zinc  paste,  shake  well,  and  as  soon  as  the  acid  is  all  neu- 
tralized the  precipitate  will  settle  readily;  dilute  to  the 
mark  with  cold  water  and  shake  well.  Filter  through  a 
large,  dry,  plaited  filter;  take  100  c.  c.  of  the  filtrate,  place 
it  in  a  250  c.  c.  flask,  add  20  c.  c.  of  the  solution  of  zinc 
sulphate,  boil,  and  titrate  with  ft  KMn04.  In  titrating 


IKON  AND  STEEL.  77 

shake  the  flask  violently  after  each  addition,  and  reheat 
toward  the  last.  The  end  reaction  is  the  production  of  a 
faint  permanent  rose  color. 

VOLUMETRIC  PROCESS. 

No.  3. 

Take  2  grins,  of  steel,  dissolve  in  30  c.  c.  of  1.20  HNO3, 
when  dissolved  boil  for  5  minutes,  dilute  with  water, 
transfer  to  a  500  c.  c.  flask,  add  dry  sodium  carbonate  till 
the  solution  turns  red,  then  add  an  excess  of  oxide  of  zinc 
paste,  dilute  to  the  mark  with  cold  water,  shake  well,  and 
filter  through  a  large,  dry,  plaited  filter.  Take  200  c.  c.  of 
the  filtrate,  add  some  of  the  oxide  of  zinc  paste,  heat 
rapidly  till  the  solution  boils,  and  titrate  with  ^  KMn04. 
&  factor  of  Mn  =  .00165. 

Estimation  of  Total  Carbon. 

[  See  Illustration  on  Page  78.] 

A  and  B  are  for  removing  C02  from  the  air;  A  is  filled 
one-third  full  with  a  solution  of  KHO,  and  B  is  filled 
with  soda-lime.  C  is  a  funnel  tube  for  transmitting  the 
solutions  into  the  generating  flask  D;  it  is  connected  by 
a  rubber  tube,  and  cork  ( a )  with  the  U-tube  B,  so  that 
all  the  air  which  enters  the  apparatus  at  this  end  is  freed 
from  CO2;  it  is  also  provided  with  a  stop-cock.  D  is  the 
generating  flask.  E  is  a  flask  for  condensing  any  vapor 
that  may  pass  over  during  the  operation;  the  bottom  is 
covered  with  strong  H2SO4;  the  entrance  tube  passes 
just  through  the  cork  and  the  exit  tube  extends  down  to 
within  one-quarter  of  an  inch  of  the  H2SO4;  the  flask 
must  be  immersed  in  a  beaker  of  cold  water.  F  is  an 
eight  inch,  three  bulb  U-tube,  filled  to  the  mark  ( b )  with 
strong  H2SO4.  G  is  an  eight  inch,  straight  U-tube,  filled 
with  granular  calcium  chloride.  H  is  an  eight  inch 
straight  U-tube,  the  left  arm  filled  with  anhydrous  cop- 
per sulphate,  and  the  right  arm  with  granular  calcium 
chloride.  K  is  a  potash  bulb  filled  to  the  mark  (c)  with 
KHO  (1.27  sp.  gr.);  there  is  connected  with,  and  fastened 
to  it,  a  four  inch,  straight  U-tube  L,  the  upper  arm  filled 


IRON  AND  STEEL.  79 

with  soda-lime,  and  the  lower  arm  with  granular  calcium 
chloride.  K  and  L  are  for  the  absorption  of  the  carbon 
dioxide.  M  is  its  guard  tube,  tne  left  arm  filled  with 
granular  calcium  chloride,  and  the  right  with  soda-lime. 
O  is  an  aspirator  bottle,  which  holds  five  litres  of  water. 
N  is  a  funnel  for  collecting  the  carbon. 

If  the  corks  and  rubber  tubing  are  new,  boil  in  a  solu- 
tion of  Cr03  in  H2S04  and  wash  thoroughly  before  use. 

The  combustion  should  be  made  in  a  room  as  free  as 
possible  from  acid  fumes,  and  blank  tests  should  be  made 
and  the  guard  tubes  increased  till  a  constant  weight  of 
the  potash  bulb  is  obtained. 

Dissolving  the  Iron  or  Steel. — Weigh  out  3  grms.  of 
the  fine  iron  or  steel,  add  200  c.c.  of  the  double  chloride 
of  copper  and  ammonium  solution,  stir  the  solution  fre- 
quently, and  after  a  few  minutes  apply  a  gentle  heat  (50° 
or  60°  C.).  When  the  iron  and  the  precipitated  copper 
have  been  dissolved,  add  a  few  drops  of  HC1  to  dissolve 
the  thin  film  of  oxide  of  iron  which  has  formed  on  the 
surface.  The  carbon  is  now  collected  in  the  funnel  N", 
which  is  loosely  stopped  with  a  small  quantity  of  purified 
asbestos.  Hot  water  is  first  run  through  the  filter,  then 
the  solution ;  the  residue  is  washed  once  with  the  double 
chloride,  and  then  with  hot  water,  until  the  wash  water 
gives,  with  AgNO3,  no  test  for  chlorine.  The  funnel  is 
then  broken  into  three  pieces,  by  scratching  at  d  and  e 
with  a  file  and  applying  a  hot  iron;  the  pieces,  with  the 
carbonaceous  residue,  are  next  introduced  into  flask  D. 
The  whole  apparatus  is  now  carefully  connected,  and  the 
aspirator  set  running,  valves  1  and  3  being  open  and  2 
closed;  and  one  litre  of  air  drawn  through;  now  close 
valve  3  and  open  valve  2.  After  standing  thirty  minutes 
disconnect  K  and  L  and  weigh  them.  Ke-connect  K  and 
L,  close  valves  1  and  2,  remove  the  cork  (a)  and  by  means 
of  a  funnel  introduce  into  C,  90  c.c.  of  the  solution  of 
CrO3  and  H2S04.  (The  amount  to  be  used  of  this  solution 
will  depend  upon  the  carbon  present.  For  3  grms,  of 
steel  with  one  per  cent,  of  carbon  or  less,  use  90  c.c.  Tor 


80  IRON  AND  STEEL, 

pig  iron,  or  high  carbon,  use  at  least  twice  this  amount, 
or  take  less  of  the  metal  in  order  to  maintain  about  the 
same  ratio  between  the  .carbon  and  oxidizing  reagent). 
Then  insert  cork  (a)  and  open  valve  3,  and  as  soon  as  air 
bubbles  commence  coming  through  K,  open  valve  1  and 
allow  the  solution  to  flow  gradually  into  D.  Now  close 
valve  1  and  apply  heat  to  D ;  shake  D  carefully  to  insure 
thorough  contact  of  its  contents,  and  continue  the  heat 
till  white  fumes  appear,  or,  to  incipient  ebullition.  Re- 
move the  lamp  and  gradually  open  valve  1  till  wide  open ; 
when  the  aspirator  O  is  half  empty,  open  valve  3  so  that 
the  air  bubbles  will  come  over  more  rapidly.  At  first 
the  bubbles  should  not  come  through  faster  than  three 
in  a  second,  and  at  no  time  fast  enough  to  throw  the 
potash  solution  in  K  into  the  exit  tube.  When  the  aspi- 
rator O  is  nearly  empty  close  valve  3,  and  in  about  five 
minutes  open  valve  2;  allow  the  apparatus  to  stand 
thirty  minutes,  then  disconnect  K  and  L  and  weigh 
them;  the  increase  of  weight  is  the  weight  of  C02,  of 
which  27.3  %  is  C. 

Estimation  of  Graphite. 

Take  about  2  grins,  of  iron,  add  an  excess  of  HC1 
(1.12  sp.  gr.),  heat  moderately  until  no  more  gas  is 
evolved,  filter  through  purified  asbestos,  wash  with  hot 
water,  then  with  a  solution  of  potash,  next  with  alco- 
hol, and  lastly  with  ether;  dry  thoroughly  and  oxidize 
with  CrO3. 

Colorimetric  Determination  of  Combined 
Carbon. 

Select  for  color  standards,  steels,  which  are  as  nearly 
like  the  samples  to  be  treated  as  possible,  both  as  to 
chemical  composition  and  mechanical  treatment,  and 
treat  the  standards  and  samples  to  be  tested  exactly 
alike  in  working. 

A  widely  varying  chemical  composition  in  other  ele- 
ments than  carbon  and  iron,  and  the  mechanical  treat- 


IEON  AND  STEEL.  81 

ment,  as  well  as  the  varying  modes  of  carrying  on  the 
analysis,  all  make  differences  in  the  intensity  and  shade 
of  color  given  by  combined  carbon  in  steel  to  its  nitric 
acid  solution. 

The  mechanical  state  of  division  of  the  standard  and 
samples  to  be  treated  must  be  about  the  same. 

Drillings  are  generally  used,  since  they  are  less  liable 
to  contain  foreign  matter,  and  as  a  rule,  are  sufficiently 
coarse  to  prevent  too  rapid  solution. 

One-tenth  of  a  grm.  is  usually  taken,  although  varying 
amounts  up  to  five-tenths  are. used. 

I  prefer  to  take  one-tenth  of  a  grm.  as  being  more 
convenient  to  work  with,  although  the  error  is  slightly 
less  with  a  greater  weight. 

The  amount  of  nitric  acid  (1.20  sp.  gr.)  to  be  used 
will  depend  upon  the  per  cent,  of  carbon  as  well  as  upon 
the  amount  of  steel  taken.  For  0.1  grm.  of  steel,  with 
carbon  from  0.00  per  cent,  up  to  0.50  per  cent,  use  3  c.  c.  of 
acid;  from  0.50  up  to  1.00  per  cent,  carbon  use  4  c.  c.;  from 
1.00  up  to  1.75  per  cent,  of  carbon  use  5  c. c.;  above  1.75  per 
cent,  of  carbon  use  8  c.  c. 

Place  the  weighed  samples  in  5  inch  test  tubes,  and 
immerse  them  in  cold  water,  then  run  into  each  tube, 
gradually,  3  c.  c.  of  HNO3  ( 1.20  sp.  gr.)  for  each  0.1  grm.  of 
steel  taken.  ( The  nitric  acid  must  be  free  from  chlorine, 
nitrous  fumes,  and  organic  matter.)  Allow  them  to  stand 
until  all  action  has  ceased  in  the  cold. 

The  samples  under  examination  are  now  compared 
with  the  standard  by  removing  the  tubes  successively 
from  the  water,  and  more  acid  is  added  to  the  darker 
samples  if  it  is  deemed  necessary.  The  cold  water  in 
which  the  tubes  are  immersed  is  now  rapidly  brought  to 
boiling,  and  boiled  for  fifteen  minutes  if  the  steel  has  less 
than  0.15  per  cent,  carbon,  for  twenty  minutes  if  between 
0.15  and  0.30,  and  for  thirty  minutes  if  between  0.30  and 
0.80,  and  for  forty-five  minutes  if  above  0.80  per  cent,  car- 
bon. 

If  the  solution  becomes  turbid,  due  to  a  deposit  of 
7 


82  IRON  AND  STEEL. 

nitric  acid  and  oxide  of  iron,  then  the  sample  should  not 
be  heated  above  70°  C. 

The  test  tubes  should  be  shaken  several  times  during 
the  boiling,  which  should  be  performed  in  a  moderately 
dark  room  or  closet,  and  the  water  in  the  bath  should  be 
kept  at  least  on  a  level  with  the  solutions  in  the  tubes, 
which  can  be  accomplished  by  adding  from  time  to  time 
boiling  water  to  the  bath. 

After  the  boiling,  remove  the  test  tubes  from  the  bath 
and  plunge  them  into  cold  water,  and,  when  cold,  place 
them  in  a  rack  and  exclude  the  light,  then  add  to  each 
tube  3  c.  c.  of  water  for  each  0.1  grm.  of  steel  taken,  which 
will  destroy  the  tint  of  oxide  of  iron.  Shake  the  tubes, 
and  if  there  is  any  graphite  present  filter  through  a  very 
small  dry  filter. 

When  placing  the  tubes  in  the  rack  after  cooling,  ar- 
range them  according  to  the  depth  of  color,  the  darkest 
one  at  one  extremity  and  the  lightest  at  the  other. 

For  comparing  the  colors  use  a  pair  of  graduated 
tubes,  with  %  or  J^  inch  internal  diameter;  these  tubes 
must  be  made  of  colorless  glass,  must  have  the  same  in- 
ternal bore  and  thickness  of  glass  walls,  and  must  be 
calibrated. 

In  matching  the  colors  use  a  camera-shaped  box, 
painted  black  inside,  with  two  holes  through  the  upper 
part  near  the  small  end  for  inserting  the  tubes,  and  with 
a  piece  of  pure,  white  filter-paper  fastened  over  the  small 
end. 

Take  the  test  tube  containing  the  standard  and  com- 
pare it  with  the  rack  of  samples,  and  select  the  one  which 
has  the  same  or  a  slightly  darker  color,  as  the  beginning 
point.  Transfer  the  standard  to  one  of  the  graduated 
tubes,  and  dilute  it  with  water  so  that  1  c.  c.  represents 
0.1  or  0.05  per  cent,  of  carbon.  If  we  take  0.1  grm.  of  a 
0.30  per  cent,  carbon  steel,  and  after  dissolving  dilute  it 
to  6  c.  c.,  each  c.  c.  represents  0.05  per  cent,  of  carbon 
( 0.30  -4-  6  =  0.05 ).  If  our  standard  is  a  0.31  per  cent,  car- 
bon, then  we  must  dilute  it  to  6.2  c.  c.  (0.31  -*-  6.2  =  0.05). 


TITANIC  IKON.  83 

Having  thus  diluted  the  standard,  take  the  other  gradu- 
ated tube  and  empty  into  it  the  test-tube  which  has  been 
selected  as  the  beginning  point,  place  the  two  in  the 
camera  box,  and  if  the  sample  under  examination  is 
darker  than  the  standard,  dilute  it  with  water  until  it 
has  the  same  color  as  the  standard;  note  the  number  of 
c.  c,  and  multiply  them  by  0.05;  this  gives  the  per  cent,  of 
carbon.  Compare  all  the  darker  samples  in  the  same 
manner.  Now  dilute  the  standard  with  an  equal  volume 
of  water,  then  each  c.  c.  represents  0.025  per  cent,  of  car- 
bon, and  compare  the  lighter  colors  with  it  in  the  same 
manner. 


TITANIC  IRON. 

Estimation  of  Silica,  Titanium,  and  Iron. 

Fuse  in  a  platinum  crucible  enough  KHSO4  to  form  in 
the  bottom  a  mass,  one-quarter  of  an  inch  thick.  Weigh 
0.2  grms.  of  the  ore,  mix  it  thoroughly  with  3  grms.  of  the 
finely  pulverized,  fused  KHS04  and  charge  it  into  the 
crucible,  and  place  on  top  of  all  some  fine,  fused  KHS04r 
cover  the  crucible,  and  heat  very  moderately  for  five  min 
utes.  (The  heat  must  be  just  sufficient  to  expel  a  very 
small  amount  of  S03).  Now  increase  the  flame,  and  so 
place  the  crucible  that  the  bottom  will  be  in  the  cool  part 
of  the  flanie  (that  is,  two  or  three  inches  from  the  burner, 
according  to  the  size  of  the  flame),  continue  this  heat  five 
minutes,  then  remove  the  lamp,  and  examine  the  charge. 
It  will  be  fluid,  and  one  can  readily  see  whether  or  not 
the  ore  is  all  fused.  If  not,  heat  a  little  longer,  and  add 
more  fused  KHS04  if  necessary. 

When  fused,  allow  it  to  cool  till  it  begins  to  solidify, 
then  pour  into  a  hot  porcelain  evaporating  dish  as  much 
of  it  as  possible,  place  the  crucible  in  the  dish,  and  when 
cold  dissolve  in  cold  water  and  filter. 

Res. {a}  =  Silica  and  calcium  sulphate.  While  yet 
moist  wash  the  residue  with  a  saturated  solution  of  sodium 


84  CHROME  IEON  QBE. 

hyposulphite,  which  will  dissolve  the  calcium  sulphate, 
and  finally  with  distilled  water  to  remove  the  hyposulphite. 
This  wash  water  must  not  be  added  to  flit.  (a). 

Filt.  (a)  contains  the  titanic  acid,  the  iron  and  some 
lime.  Dilute  to  500  c.  c.,  add  a  few  drops  of  nitric  acid  to 
prevent  the  ferric  iron  from  coming  down  with  the  titanic 
acid  and  boil  for  some  time,  maintaining  the  bulk  of  the 
solution  by  adding  from  time  to  time  hot  water.  Filter.* 

Pp.  (6)  =  TiO2.  Dry  and  ignite,  cool,  add  a  little  dry 
ammonium  carbonate,  and  again  ignite  to  expel  any  sul- 
phuric acid  that  may  be  present. 

Filt.  (6)  contains  the  iron  and  part  of  the  lime;  add  to 
it  the  wash  water  from  res.  (a),  and  then  determine  the 
total  iron,  and  the  lime. 


CHROME  IRON  ORE. 

Estimation  of  Cr2O3. 

Take  0.5  grm.  of  the  very  finely  pulverized  ore  and 
mix  it  with  6  grms.  of  fused  KHSO4  in  a  large  platinum 
crucible,  fuse  for  15  minutes  at  as  low  a  heat  as  possible, 
then  raise  the  heat  gradually  till  the  full  heat  of  the  Bun- 
sen  burner  has  been  attained;  now  apply  the  blast  and 
heat  for  15  minutes  longer;  cool,  add  3  grms.  of  dry  sodium 
carbonate,  fuse,  and  project  into  the  fused  mass,  from 
time  to  time,  potassium  nitrate  till  about  3  grms.  have 
been  added.  This  last  fusion  will  require  about  one  hour. 
The  whole  operation  must  be  carefully  watched  from  the 
first  and  the  contents  of  the  crucible  not  allowed  to  run 
over  the  sides.  Dissolve  the  fused  mass  in  boiling  water, 
filter  while  hot,  and  wash  with  hot  water  =  filt.  (a). 

Res.  (a).  Digest  with  HC1  for  three  hours;  if  a  dark 
residue  remains,  filter,  throw  away  the  filtrate,  and  fuse 
the  residue  as  above,  and  add  the  filtrate  to  filtrate  (a). 

*Crookes  197. 


LEAD  SLAGS.  85 

Fttt.  (a).  Add  an  excess  of  ammonium  nitrate,  evap- 
orate on  a  water  bath,  nearly  to  dryness,  or  until  all  of 
the  liberated  ammonia  has  been  expelled,  then  add  water 
and  filter. 

Filt.  (6).  Add  a  few  drops  of  H2SO4  and  then  a  small 
piece  of  bisulphite  of  soda,  and  boil  till  all  the  CrO3  is 
reduced  to  Cr2O3  and  the  excess  of  sulphurous  acid  has 
been  expelled,  (the  solution  will  be  bright  green).  Now 
add  ammonia  in  slight  excess  and  boil  till  the  excess  is 
expelled,  filter  and  wash  with  hot  water.  The  filtrate 
should  be  colorless. 


LEAD  SLAGS. 

Proximate  Analysis. 

The  silver  and  lead  are  generally  estimated  in  the  dry 
way. 

Estimation  of  Silica.— Dissolve  a  weighed  sample  (1 
grm.)  in  strong  HC1,  add  some  HXO3  to  oxidize  the  iron, 
evaporate  to  dryness,  take  up  with  HC1  and  water,  filter 
and  wash  by  decantation  with  boiling  water.  The  residue 
of  silica,  with  some  foreign  matter,  is  ignited  in  the  usual 
way.  The  filtrate  can  be  used  to  estimate  alumina,  iron, 
lime,  and  magnesia  (see  Blast  Furnace  Slag). 

Estimation  of  Iron.— Dissolve  1  grm.  of  the  slag  in 
strong  HC1,  and  filter;  if  copper  is  present  it  must  be 
removed;  now  titrate  the  iron  with  stannous  chloride  and 
ft  K2Cr207. 

Estimation  of  Manganese. — Dissolve  a  weighed  sam- 
ple in  HC1,  add  enough  HN03  to  oxidize  the  iron,  then 
add  a  moderate  excess  of  H2SO4  and  evaporate  till  white 
fumes  (SO3)  are  given  off;  cool,  dilute  with  water,  and 
filter;  titrate  the  filtrate  with  ft  KMnO4. 

Estimation  of  Lime. — Dissolve  0.5  grm.  of  the  slag  in 
aqua  regia,  and  filter;  add  to  the  filtrate  ammonia  in  slight 
excess,  and  boil:  continue  the  boiling  and  add  gradually 


86         COPPER  ORES  AND  PRODUCTS. 

a  saturated  solution  of  oxalic  acid  until  the  iron  is  dis- 
solved, then  add  ammonia  till  a  slight  precipitate  of  iron 
is  formed,  now  add  very  cautiously  more  oxalic  acid  until 
the  iron  is  dissolved,  boil  for  fifteen  minutes  after  the 
last  addition  of  oxalic  acid,  and  then  filter.  (If  iron  is  pre- 
cipitated with  the  lime,  dissolve  in  HC1  and  reprecipitate.) 
Titrate  the  precipitate  for  lime  according  to  directions 
given. 


COPPER    ORES    AND    PRODUCTS. 
Estimation  of  Copper  by  the  Battery. 

A  method  for  estimating  copper  in  all  ores  and  sub- 
stances, which  do  not  contain  elements  that  are  precipi- 
tated by  the  battery  from  acid  solutions. 

Take  2  grms.  if  the  ore  carries  more  than  10  per  cent, 
of  copper,  add  5  c.  c.  of  strong  H2SO4,  then  a  little  HNO3 
from  time  to  time  until  action  ceases;  heat  on  a  sand  bath 
until  white  fumes  appear,  and  the  mass  is  nearly  dry;  cool, 
add  30  c.  c.  of  water,  boil  and  filter,  wash  with  water  acid- 
ulated with  H2SO4  ( if  there  remains  a  black  residue  treat 
it  as  before).  Place  the  filtrate,  or  a  part  of  it,  in  a 
weighed  platinum  dish,  then  place  the  dish  in  the  circuit 
of  a  moderately  strong  battery;*  when  the  solution 
has  lost  its  color,  test  a  drop  of  it  with  H2S  water;  if  any 
copper  remains  in  the  solution.,  a  dark  precipitate  will  be 
formed.  Wash  the  precipitated  copper  two  or  three  times 
with  hot  water,  then  with  alcohol;  ignite  the  remaining 
alcohol  and  when  burnt  off,  weigh;  if  the  copper  solution 
is  too  strong  the  copper  will  not  all  adhere  to  the  dish, 
but  will  appear  as  loose,  granular  copper;  this  will  also 
happen  if  the  current  of  the  battery  is  too  strong. 

*  By  using  two  Bunsen  elements  and  heating  the  copper  solution 
to  70°  or  80°  C.,  the  copper  will  be  precipitated  in  four  hours.  (Classen 
on  electrolysis  65.) 


ZINC  ORES.  87 

Estimation  of  Copper  by  Potassium  Cyanide. 

Dissolve  the  sample  as  in  the  preceding  method,  and 
filter  into  a  large  beaker,  in  which  has  been  placed  a  rod 
of  zinc  to  which  has  been  fastened  a  strip  of  platinum 
foil.  When  the  copper  is  all  precipitated,  remove  the 
zinc,  and  wash  the  copper  by  decantation,  using  a  little 
sulphuric  acid  in  the  wash  water.  Dissolve  the  copper  in 
the  least  quantity  of  nitric  acid  possible,  add  about  50  c.  c. 
of  water,  then  add  NH^OH  till  the  precipitate  which  first 
forms  is  just  dissolved,  now  dilute  to  a  given  number  of 
c.  c.  and  titrate  with  standard  Potassium  Cvanide. 


ZINC   ORES. 

Estimation  of  Zinc. 

For  rich  ores  take  0.5  grm.,  for  poor  ores  1  to  2  grms. 
Dissolve  the  ore  in  aqua  regia,  evaporate  to  dryness,  and 
treat  the  residue  with  HC1  and  water.  Pass  into  this 
strongly  acid  solution  H2S  gas  and  filter. 

Pp.  (a )  =  CuS,  etc. 

Filt.(a}.  Boil  and  add  a  few  crystals  of  KC1O3  to 
oxidize  the  sulphur  and  iron,  continue  the  boiling  until 
the  odor  of  Cl  has  disappeared ;  cool,  and  add  NH4OH  in 
slight  excess,  boil,  and  filter.  If  there  is  much  iron,  dis- 
solve the  precipitate  in  HC1  and  reprecipitate  with  am- 
monia, and  filter.  Unite  the  filtrates. 

Pp.  (6)  =  Fe203,  etc. 

Filt.  (6).  Neutralize  with  HC1,  and  then  add  15  c.  c. 
more  of  HC1,  and  dilute  to  200  or  300  c.  c.  Take  30  to  50 
c.  c.  of  this  solution,  heat  nearly  to  boiling,  add  a  few 
drops  of  a  solution  of  uranium  acetate,  and  titrate  with 
the  standard  solution  of  Potassium  Ferrocyanide. 

While  the  above  is  for  the  estimation  of  zinc  only,  it 
can  be  used  for  estimating  copper  and  zinc  in  certain  ores 


88        AESENIC  ORES  AND  PRODUCTS. 

and  lead  furnace  slags.  For  this  purpose  take  Pp.(a\ 
dissolve  in  HC1,  boil  and  add  a  few  crystals  of  KC1O3  and 
continue  the  boiling  till  the  odor  of  chlorine  disappears; 
filter,  and  add  to  the  filtrate  NH4OH  and  titrate  with 
Potassium  Cyanide  as  directed  under  copper  ores  and 
products. 


ARSENIC  ORES  AND   PRODUCTS. 

Estimation  of  Arsenic. 

Take  o.5  grm.  of  the  very  fine  ore,  and  fuse  it,  in  a 
large  porcelain  crucible,  with  from  6  to  10  times  its  weight, 
of  a  mixture  of  equal  parts  of  Na2CO3  and  KSTO3.  Apply 
a  moderate  heat  at  first,  and  near  the  top  of  the  crucible 
if  possible.  When  thoroughly  fused  and  no  more  bubbles 
escape,  cool,  and  dissolve  in  hot  water.  Filter  and  acid- 
ulate the  filtrate  with  HNO3,  and  boil  till  CO2  is  all 
expelled;  cool  and  exactly  neutralize  with  NH4OH.  If  a 
precipitate  is  formed  ( alumina,  etc.),  filter  it  off.  Add  to 
this  solution  silver  nitrate  in  excess,  stir  well,  then  add 
from  a  burette  (a  drop  at  a  time)  a  dilute  solution  of 
NH4OH  ( 1  part  NH4OH  to  ten  parts  water )  till  neutral, 
or  slightly  alkaline;  stir  thoroughly.  The  arsenic  will  be 
precipitated  as  the  brick-red  arsenate  of  silver  ( Ag3  AsO4). 
Filter  and  wash  the  precipitate  with  cold  water.  Dissolve 
the  precipitate  on  the  filter  with  dilute  HN  03,  add  to  this 
solution  a  few  drops  of  ferric  nitrate,  and  titrate  with  •& 
Ammonium  Sulphocyanate. 

Each  c.  c.  =  .0025  As. 

If  the  ore  carries  a  large  per  cent,  of  arsenic,  first 
digest  it  with  strong  H]ST03,  evaporate  to  dryness,  and 
then  add  the  fusing  mixture  and  fuse  as  given  above. 


MANGANESE  ORES. — INSOLUBLE  SILICATES.        8$ 
MANGANESE  ORES. 

Technical  Examination  of  Manganese  Ores 
used  for  Bleaching  Purposes. 

Pulverize  2  or  3  grms.  very  fine  and  dry  at  120°  C.  in 
an  air  bath.  Weigh  out  about  0.5  grm.,  place  in  a  250  c.  c. 
flask  and  add  6  grms.  of  crystalized  ammonio-ferrous 
sulphate,  and  about  20  c.  c.  of  water,  warm  till  the  salt  is 
dissolved,  then  add  strong  H2SO4  and  heat  till  the  ore  is 
completely  decomposed.  Now  titrate  the  excess  of  the 
double  iron  salt  with  -^  K2Cr2O7,  and  multiply  the  c.  c.  of 
•ft  K2Cr2O7  required  by  .0392;  the  product  will  be  the  num- 
ber of  grms.  of  the  double  iron  salt  undecomposed.*  De- 
ducting this  amount  from  the  grms.  taken  we  will  have 
the  grms.  of  the  double  iron  salt  that  have  been  oxidized, 
which  multiplied  by  0.111  will  give  the  amount  of  per- 
oxide of  manganese  in  the  weight  taken. 


INSOLUBLE  SILICATES. 

Estimation  of   Potash  and  Soda  in  Feldspar,, 
Etc. 

Take  0.5  grm.  of  the  finely  pulverized  silicate  and  mix 
it  with  0.5  grm.,  or  a  little  more,  of  NH4C1  in  an  agate 
mortar;  then  add  4  grms.  of  carbonate  of  lime  in  three 
portions,  mixing  intimately  after  each  addition.  Charge 
this  mixture  into  a  platinum  crucible.  Place  the  crucible 
in  an  inclined  position  on  the  triangle  and  apply  a  gentle 
heat  (commencing  at  the  top  and  gradually  carrying  it 
toward  the  bottom)  until  the  NH4C1  is  completely  decom- 

*If  &  KMn04  is  used,  the  end  reaction  must  be  determined  by 
using  potassium  ferricyanide  as  in  titrating  with  KsCrgO? ;  for  I  have- 
found  that  solutions  containing  a  considerable  quantity  of  sulphate  of 
manganese  will  reduce  KMnC>4,  and  the  rose  color  will  not  be  obtained 
till  long  after  the  ferrous  iron  has  all  been  oxidized,  if  at  all. 


90  INSOLUBLE  SILICATES. 

posed.  This  will  take  from  5  to  10  minutes.  Now  place 
the  crucible  in  the  upright  position,  and  apply  a  bright 
red  heat  for  from  40  to  60  minutes.  Cool  the  crucible; 
when  cold  the  contents  will  be  found  to  be  a  semi-fused 
mass;  place  in  an  evaporating  dish,  add  water,  and  heat 
till  the  mass  slakes;  remove  the  crucible,  washing  it  thor- 
oughly with  water,  and  digest  the  mass  one  hour  longer 
or  till  completely  disintegrated.  Filter  and  wash  well. 
The  nitrate  contains  all  the  alkalies  of  the  mineral,  and 
some  calcium  chloride  and  caustic  lime;  add  some  ammo- 
nium carbonate,  and  concentrate  to  about  50  c.  c.;  then 
add  a  little  more  ammonium  carbonate  and  a  few  drops 
of  ammonia,  and  filter;  to  this  filtrate  add  a  few  drops  of 
ammonium  carbonate,  and  concentrate;  if  a  precipitate  is 
formed,  filter  it  off  and  repeat  the  last  operation  till  a 
precipitate  ceases  to  be  formed;  now  evaporate  to  dryness 
in  a  weighed  platinum  dish  on  a  water  bath ;  when  dry, 
heat,  at  first  moderately,  over  the  Bunsen  burner  until 
the  KH4C1  is  driven  off,  and  then  gradually  increase  the 
heat  to  faint  redness;  cool,  and  weigh.  This  weight  is 
the  chlorides  of  the  alkalies,  or  the  weight  of  mixed 
chlorides. 

Indirect  Determination  of  the  Potash  and  Soda  in  the 
Mixed  Chlorides. — Dissolve  the  mixed  chlorides  in  water 
and  determine  by  titration  with  ft  AgNO3  the  total 
chlorine:  Then  by  means  of  the  following  formula?  the 
^quantities  of  NaCl  and  KC1  are  determined. 

TV  =  weight  of  mixed  chloride. 

C    =  weight  of  chlorine. 
Nad  =  C  X  7.6311  —  W  X  3.6288. 
KC1    =  W  X  4.6288  —  C  X  7.6311. 


SUPERPHOSPHATES.  91 

SUPERPHOSPHATES. 

Method  for  Determining  Phosphoric  Acid 
and  Moisture. 

PREPARATION  OF  REAGENTS. 

(1)  To  prepare  ammonium  citrate  solution. — Mix  370 
grams  of  commercial  citric  acid  with  1,500  cubic  centime- 
ters of  water;  nearly  neutralize  with  crushed  commercial 
carbonate  of  ammonia;  heat  to  expel  the  carbonic  acid; 
cool;  add  ammonia  until  exactly  neutral  (testing  by  sat- 
urated alcoholic  solution  of  coralline)  and  bring  to  volume 
of  two  litres.    Test  the  gravity,  which  should  be  1.09  at 
20°,  before  using. 

(2)  To  prepare  molybdic  solution.— Dissolve  100  grams 
of  molybdic  acid  in  400  grams  or  417  cubic  centimeters  of 
ammonic  of  specific  gravity  0.96,  and  pour  the  solution 
thus  obtained  into  1,500  grams  or  1,250  cubic  centimeters 
of  nitric  acid  of  specific  gravity  1.20.    Keep  the  mixture 
in  a  warm  place  for  several  days,  or  until  a  portion  heated 
to  40°  C.  deposits  no  yellow  precipitate  of  ammonium 
phospho-molybdate.    Decant  the  solution  from  any  sedi- 
ment, and  preserve  in  glass-stoppered  vessels. 

(3)  To  prepare  ammonium  nitrate  solution.— Dissolve 
200  grams  of  commercial  ammonium  nitrate  in  water  and 
bring  to  a  volume  of  two  liters. 

(4)  To  prepare  magnesia  mixture. — Dissolve  22  grams 
of  recently-ignited  calcined  magnesia  in  dilute  hydro- 
chloric acid,  avoiding  excess  of  the  latter.    Add  a  little 
calcined  magnesia  in  excess,  and  boil  a  few  minutes  to 
precipitate  iron,  alumina,  and  phosphoric  acid,  filter,  add 
280  grams  of  ammonium  chloride,  700  cubic  centimeters 
of  ammonia  of  specific  gravity  0.96,  and  water  enough  to 
make  the  volume  of  two  liters.    Instead  of  the  solution 
of  22  grams  of  calcined  magnesia  110  grams  of  crys- 
tallized magnesium  chloride  (MgCl2,  6H2O)  may  be  used. 

(5)  Dilute  ammonia  for  toashing—One  volume  am- 
monia of  specific  gravity  0.96  mixed  with  three  volumes 


92  SUPERPHOSPHATES. 

of  water,  or  usually  1  volume  of  concentrated  ammonia 
with  6  volumes  of  water. 

(1)  Preparation  of  sample.— The  sample  should  be 
well  intermixed  and  properly  prepared,  so  that  separate 
portions  shall  accurately  represent  the  substance  under 
examination,  without  loss  or  gain  of  moisture. 

(2)  Determination  of  moisture. — (a)    In  potash  salts, 
nitrate  of  soda,  and  sulphate  of  ammonia  heat  1  to  5  grams 
at  130°  C.  till  the  weight  is  constant,  and  reckon  water 
from  the  loss.  (6)  In  all  other  fertilizers  heat  2  grams,  or 
if  the  sample  is  too  coarse  to  secure  uniform  lots  of  2 
grams  each,  5  grams  for  five  hours  at  100°  in  a  steam  bath. 

(3)  Water-soluble  phosphoric  acid.— Bring  2  grams  on 
a  filter,  add  a  little  water,  let  is  run  out  before  adding 
more  water,  and  repeat  this  treatment  cautiously  until  no 
phosphate  is  likely  to  precipitate  in  the  filter.  If  the  wash- 
ings show  turbidity  after  passing  the  filter  clear  up  with 
acid.    When  the  substance  is  nearly  washed  in  this  man- 
ner it  is  transferred  to  a  mortar  and  rubbed  with  a  rubber 
tipped  pestle  to  homogeneous  paste  (but  not  further  pul- 
verized), then  returned  to  the  filter  and  washed  with 
water  until  the  filtrate  measures  not  less  than  250  cubic 
centimeters.  Mix  the  washings.  Take  an  aliquot  (usually 
corresponding  to  y%  gram  of  the  substance)  and  determine 
phosphoric  acid,  as  under  total  phosphoric  acid. 

(4)  Citrate-insoluble  phosphoric  acid.— Wash  the  res- 
idue of  the  treatment  with  water  into  a  150  cubic  centi- 
meter flask  with  100  cubic  centimeters  of  strictly  neutral 
ammonium  citrate  solution  of  1.09  density,  shred  and  add 
the  filter  paper,  cork  the  flask  securely,  place  in  a  water 
bath  with  constant  temperature  of  65°  C.,  and  digest  for 
thirty  minutes  at  this  temperature  with  frequent  shak- 
ing, filter  the  warm  solution  quickly  and  wash  with  water 
of  ordinary  temperature.    Transfer  the  filter  and  its  con- 
tents to  a  capsule,  ignite  until  the  organic  matter  is  de- 
stroyed, treat  with  10-to  15  cubic  centimeters  of  concen- 
trated hydrochoric  acid,  digest  over  a  low  flame  until  the 
phosphate  is  dissolved,  dilute  to  200  cubic  centimeters, 


SUPERPHOSPHATES.  93 

mix,  pass  through  a  dry  filter,  take  an  aliquot  and  deter- 
mine phosphoric  acid  as  under  total. 

In  case  a  determination  of  citrate-insoluble  phosphoric 
acid  is  required  in  non-acidulated  goods,  it  is  to  be  made 
by  treating  2  grams  of  the  phosphatic  material  without 
previous  washing  with  water,  precisely  in  the  way  above 
described,  except  that  in  case  the  substance  contains 
much  animal  matter  (bone,  fish,  &c.)  the  residue  insol- 
uble in  ammonium  citrate  is  to  be  digested  with  HC1  and 
KC1O3,  as  described  below. 

(5)  Total  phosphoric  acid.— Weigh  2  grams  into  a  flask 
or  beaker,  add  30  cubic  centimeters  concentrated  hydro- 
chloric acid,  heat  and  add  cautiously  and  in  small  quan- 
tities at  a  time  about  0.5  gram  finely-powdered  potassium 
chlorate.  Digest  at  a  gentle  heat  until  all  phosphates  are 
dissolved  and  all  organic  matter  destroyed,  dilute  to  200 
cubic  centimeters;  mix;  pass  through  a  dry  filter;  take 
50  cubic  centimeters  of  filtrate;  neutralize  with  ammonia; 
for  every  decigram  of  P2O5  that  is  present,  add  50  cubic 
centimeters  of  molybdic  solution.  Digest  at  about  65°  C. 
for  one  hour  filter  and  wash  with  ammonium  nitrate  solu- 
tion. (Test  the  filtrate  by  renewed  digestion  and  addition 
of  more  molybdic  solution.)  Dissolve  the  precipitate  on  the 
filter  with  ammonia  and  hot  water,  and  wash  into  a  beaker 
to  a  bulk  of  not  more  than  100  cubic  centimeters.  Nearly 
neutralize  with  hydrochloric  acid,  cool,  and  add  magnesia 
mixture  from  a  burette;  add  slowly  (one  drop  per  second), 
stirring  vigorously.    After  15  minutes  add  30  cubic  cen- 
timeters of  ammonia  solution  of  density  0.95.    Let  stand 
several  hours  (two  hours  is  usually  enough).     Filter; 
wash  with  dilute  ammonia;  ignite  intensely  for  10  min- 
utes and  weigh. 

(6)  Citrate-soluble  phosphoric  acid.    The  sum  of  the 
water-soluble  and  citrate-insoluble  subtracted  from  the 
total  gives  the  citrate-soluble. 


94  ANALYSIS  OF  NICKEL  SPEISS. 

ANALYSIS  OF  NICKEL  SPEISS. 

Digest  a  weighed  portion  with  strong  HC1,  at  60°-70° 
C.,  for  some  time,  afterward  bringing  to  a  boil.  Evapo- 
rate to  dryness,  take  up  with  HC1  +  H2O  and  filter.  Or, 
complete  solution  may  be  obtained  by  digesting  the  sam- 
ple in  the  above  manner  with  Br  and  afterward  taking 
up  with  HC1  and  H2O.  (This  method  of  solution  in 
Bromine  is  of  great  value  with  many  Sulphides,  especially 
where  the  S  is  to  be  estimated.) 

Res.  (a)  =  SiO2. 

Filt.  (a).  Heat  to  70°  C.  Pass  H2S  gas  through  the 
solution  1^  hour,  and  filter. 

Res.  (b)  =  Sulphides  of  Cu,  As,  Sb  etc. 

Filt.  (6).  Boil.  Oxidize  H2S  with  KC1O3,  and  expel 
excess  of  Cl  by  further  boiling.  Cool  and  precipitate 
Fe2O3  as  basic  acetate.  Filler. 

Res.  (c)  =  Iron,  etc. 

Filt.(c\  Concentrate  to  200  c.  c.  Cool.  Acidify  with 
HC1  and  add  water  solution  of  freshly  prepared  Potas- 
sium xanthate.  Filter,  and  wash  thoroughly  with  water. 

Res.  (d)  •-=  Ni,  Co,  and  Zn  as  xanthates. 

Filt.(d).    Contains  Mn  if  present. 

Wash  Res.  (d}  on  filter  with  dilute  NH4OH. 

Res.  (e)  =  Cobalt  xanthate. 

Dissolve  this  residue  in  strong  HNO3.  Evaporate 
nearly  to  dryness,  and  add  more  HNO3  +  H2SO±  and 
evaporate  again.  The  solution  should  be  concentrated. 
Add  H2C204  +  excess  of  C2H6O  and  boil,  replacing  the 
C2H6O  as  it  evaporates.  Filter  through  sand  and  wash 
with  C2H6O.  Wash  the  sand  and  Cobalt  Oxalate  into  a 
flask  and.  acidify  with  a  few  drops  of  H2SO4.  The  red 
color  may  be  neutralized  with  a  solution  of  Nickel  Sul- 
phate, after  which  titrate  the  oxalic  acid  with  ^  KMnO4. 

Filt.  (e).    Contains  Nickel  (and  Zinc  if  present). 

If  Zn  be  present,  the  solution  may  be  acidified  with 
Citric  Acid  and  treated  with  H2S  gas,  when  perfectly 
cold.  If  much  Zn  is  present  the  gas  should  be  passed  at 


REAGENTS.  95 

intervals,  for  five  minutes  at  a  time,  so  as  to  avoid  pre- 
cipitation of  Ni.  Filter  off  ZnS  and  evaporate  the  filtrate 
to  small  bulk. 

Evaporate  almost  to  dryness  with  HNO3  (cone.),  and 
repeat  with  addition  to  H2SO4.  To  the  concentrated  solu- 
tion add  Oxalic  Acid  and  further  concentrate  by  boiling. 
Add  excess  of  C2H6O  and  digest  ^  hour,  replacing  the 
C2H6O.  Filter  as  usual.  Wash  thoroughly  with  C8H6O 
and  dissolve  on  filter  with  NH4OH.  Acidify  with  H8SO4, 
neutralize  the  green  color  with  solution  of  Cobalt  Sul- 
phate and  titrate  the  H2C2O4  with  ft  KMn04.  From 
the  amount  of  H2C204  calculate  the  Nickel. 


REAGENTS. 

Fusing  Mixture. 

2  parts  NaHCO3.  2  parts  K2CO3.  1  part  KN03.  Pul- 
verize very  fine,  and  thoroughly  mix,  ( or  2  parts  anhy- 
drous Na2CO3  and  one  part  KNO3).  Test  the  mixtures  for 
sulphur,  and  if  present  determine  the  amount. 

Magnesia  Mixture. 


No.  1. 

MgCl2 101.5  grms. 

NH4C1 200.       " 

NH4OH 400.  c.  c. 

Water  to  make  one  litre. 

_  (  0.0355  grm.  P2O5. 


No.  2. 

MgS04 100.  grms. 

NH4C1 200.      " 

NH4OH... 400.  c.  c. 

Water ...800.     " 

1  c.  c.  =  (about)  0.01  grm.  P. 


1 0.0154  P. 

Stannous  Chloride. 

50  grms.  of  the  crystallized  salt,  dissolved  in  500  c.  c. 
of  one-half  strength  HC1.  This  solution  soon  deterior- 
ates, hence  should  not  be  made  up  in  large  quantities. 


96  KEAGENT8. 

Mercuric  Chloride. 

A  saturated  solution;  60  grms.  per  litre. 

Fused  KHSO4. 

Heat  some  of  the  moist  salt  in  a  platinum  dish  or  cru- 
•cible  to  quiet  fusion,  and  pour  it  on  a  porcelain  slab. 
When  cold,  pulverize  and  place  in  a  salt  mouth  bottle. 

Molybdate  Solution. 
HTo.1. 

Take  3  grms.  of  ammonium  molybdate,  add  2  c.  c. 
NH4OH  and  triturate  in  a  mortar;  then  add  20  c.  c.  of 
water  (should  dissolve);  now  pour  this  solution  slowly 
into  20  c.  c.  of  HNO3  (1.20  sp.  gr.),  keeping  it  cold. 

No.  2. 

(a)  Dissolve  100  grms.  of  MoO3  in  a  mixture  of  300  c.  c. 
of  strong  NH4OH  and  100  c.  c.  of  water. 

(6)  1250  c.  c.  of  HN03  (1.20  sp.  gr.).  Pour  a  little  of  (6) 
into  (a),  then  all  of  (a)  into  (6)  rapidly. 

These  solutions  should  staod  several  days  before  use. 

Acid  Solution  Ammonium  Nitrate. 

Water 1  litre. 

tfH4$rO3 100  grms. 

HNO3  (1.40  sp.  gr.) 15  c.  c. 

Purified  Nitric  Acid  (1.4O  sp.  gr.) 

Must  be  free  from  nitrous  acid.  If  the  bottle  contain- 
ing the  acid  has  red  fumes,  blow  air  through  the  acid 
until  the  red  fumes  disappear,  and  then  add  5  per  cent,  of 
water  and  place  the  bottle  in  a  dark,  cool  place. 

Nitric  Acid  (1.2O  sp.  gr.) 

Add  an  equal  volume  of  water  to  the  1.40  sp.  gr.  acid. 
It  must  be  free  from  HC1  and  Cl. 


REAGENTS.  97 

Hydrochloric  Acid. 

Must  be  free  from  chlorine.  If  chlorine  is  present  add 
strips  of  copper,  let  stand  until  it  will  not  give  a  test  for 
Cl,  and  then  distil. 

Tartaric  Acid. 

Tartaric  Acid 40  grms. 

Water 200  c.  c. 

Solution  BaCl2 10  c.  c. 

Boil  the  solution,  then  allow  it  to  stand  till  the  precip- 
itate has  completely  subsided,  and  decant  off  the  clear 
liquid  for  use. 

Purified  Asbestos. 

Place  a  quantity  of  good,  fibrous  asbestos  in  a  beaker, 
add  some  of  the  CrO3  solution,  then  enough  strong  H2S04 
to  thoroughly  saturate,  and  heat  for  some  time;  pour  the 
mass  into  a  funnel  and  wash  first  with  water  acidulated 
with  H2S04,  then  with  pure  water,  until  the  Cr2O3  and 
H2SO4  are  removed;  dry. 

Oxide  of  Zinc  Paste. 

Fill  a  large  sand  or  clay  crucible  with  commercial 
oxide  of  zinc,  cover  and  heat  in  a  furnace  at  a  bright  red 
heat  for  some  time,  cool,  and  triturate  with  water  to 
form  a  thin  paste.  It  should  not  reduce  KMnO4. 

Solution  of  Zinc  Sulphate.' 

Dissolve  50  grms.  of  ZnSO4  in  water  and  dilute  to  100 
c.c.;  add  to  this  KMn04  solution  until  a  faint  pink  color 
is  produced;  then  add  some  oxide  of  zinc  paste  and 
shake  thoroughly;  allow  it  to  subside,  then  filter  or  de- 
cant off  the  clear  solution  for  use. 

Pry,  Granular  Calcium    Chloride  Free  From 
Calcium  Oxide. 

Take  crystallized  calcium  chloride  in  a  porcelain  dish 
and  heat  very  carefully  (not  above  200°  C.)  till  fused, 
then  stir  constantly  until  granulated;  now  transfer  the 

8 


98  REAGENTS. 

dish  to  an  air  bath  and  heat  at  200°  C.  till  perfectly  dry. 
Keep  in  well  stoppered  bottles.  After  filling  the  U-tubes 
pass  dry  C02  for  one  hour,  then  dry  air  until  the  C03  has 
been  removed. 

Double  Chloride  of  Copper  and  Ammonium. 

No.  1. 

CuCl2,  2H2O 340  grms. 

NH4C1 214     " 

Water 1850  c.  c. 

When  dissolved  add  enough  NH4OH  to  form  a  slight 
precipitate,  allow  this  to  subside  and  use  only  the  clear 
solution.  50  c.  c.  of  this  solution  will  dissolve  1  grm.  of 
steel  or  iron. 

No.  2. 

Make  a  saturated  solution  of  the  double  chloride  of 
copper  and  ammonium  (2NH4C1,  CuCl2  +  2HaO),  add  to 
it  very  dilute  ammonia  till  a  faint  precipitate  is  produced, 
allow  it  to  stand  till  the  precipitate  has  subsided,  then 
decant  or  filter  off  the  clear  solution. 

Solution  of  CrO3  and   H2SO4. 

Take  16  grms.  CrOs  and  dissolve  in  100  c.  c.  of  water  in 
a  porcelain  dish,  add  to  this  260  c.  c.  of  strong  H2SO4.  If 
on  stirring,  this  fails  to  dissolve  the  precipitate  which  is 
first  forme'd,  add  more  H2SO4  till  it  is  dissolved,  then 
heat  to  incipient  ebulliton.  When  cold  it  is  ready  for  use. 
It  should  not  be  prepared  long  before-hand.  1  grm.  of 
iron  will  require  30  c.  c.  of  this  solution.  90  c.  c.  will 
oxidize  the  carbon  in  3  grms.  of  ordinary  steel;  the 
amount  must  be  increased  with  the  per  cent,  of  carbon. 

Anhydrous  Copper  Sulphate. 

Take  small  pieces  of  pumice  stone,  soak  them  in  a 
saturated  solution  of  copper  sulphate,  and  then  heat  them 
in  an  air  bath  for  several  hours  at  250°  C.  Cool  and  keep 
in  well  stoppered  bottles. 


REAGENTS.  99 

Standard  Copper  Sulphate. 

Dissolve  3.95  grm.  of  pure  CuSO4,  5H2O  in  water,  add 
a  few  drops  of  H2SO4,  and  dilute  to  one  litre.  1  c.  c.  will 
contain  0.001  grm.  Cu. 

Standard  Potassium  Cyanide. 

Dissolve  5  grms.  of  Potassium  Cyanide  in  300  c.c.  of 
water,  and  titrate  it  so  that  1  c.  c.  will  be  equal  to  1  c.  c. 
of  the  copper  solution. 

Mode  of  titrating.— Take  5  c.  c.  of  the  standard  copper 
solution,  add  KH4OH  till  the  precipitate  first  formed  is 
dissolved  and  the  solution  is  deep  blue  (avoid  a  large  ex- 
cess, of  NH4OH);  now  run  into  it  (cold)  from  a  burette 
potassium  cyanide  until  the  blue  color  of  the  copper 
solution  has  disappeared.  When  the  reaction  is  complete 
the  solution  will  have  a  slight  yellow  tinge. 

The  cyanide  solution  loses  strength  by  standing  and 
must  be  compared  often. 

Standard  Solution  of  Zinc  Chloride. 

Take  10  grms.  Zn,  dissolve  in  HC1,  neutralize  with 
NH4OH,  then  add  15  c.c.  HC1  and  30  grins.  NH4C1,  and 
dilute  to  one  litre. 

Standard  Potassium  Ferrocyanide. 

Take  43.2  grms.  of  the  salt,  dissolve  in  water  and 
dilute  to  one  litre.  This  should  correspond  volume  for 
volume  with  the  zinc  solution;  but  the  solutions  should 
always  be  compared;  for  this  purpose  take  10  c.c.  of  the 
zinc  solution,  dilute  to  about  50  c.  c.,  heat  nearly  to  boil- 
ing, add  a  few  drops  of  Uranium  Acetate  solution,  then 
run  in  from  a  burette  the  Potassium  Ferrocyanide  solu- 
tion, one-half  c.c.  at  a  time,  shaking  violently  after  each 
addition,  until  the  precipitate  appears  flesh  colored;  or 
place  a  few  drops  of  Uranium  Acetate  on  a  porcelain 
slab  and  add  a  drop  of  the  solution  with  a  glass  rod, 
from  time  to  time,  till  it  gives  a  flesh  color.  While  the 


100  REAGENTS. 

zinc  is  in  excess  the  precipitate  is  flocculent  and  subsides 
rapidly,  but  when  the  zinc  is  nearly  all  precipitated,  the 
precipitate  becomes  fine  and  subsides  very  slowly,  and  a 
drop  or  two  will  produce  the  flesh  color. 

Potassium  Xanthate. 

Dissolve  some  caustic  potash  in  absolute  alcohol,  filter 
if  necessary,  and  add  to  the  filtrate  a  large  excess  of  car- 
bon disulphide;  a  crystalline  mass  will  soon  form,  which 
is  brought  on  a  filter  and  quickly  washed  with  ether,  and 
dried  over  sulphuric  acid  and  paraffin.  When  dry,  place 
in  well  corked  bottles,  and  dissolve  in  water  only  the  re- 
quired amount  when  need  for  use,  for  the  solution  soon 
deteriorates. 

Zinc  Amalgam. 

Place  a  quantity  of  granulated  zinc  in  a  dish,  cover 
with  mercury,  and  add  a  very  dilute  solution  of  sulphuric 
acid,  and  stir  till  action  ceases;  then  place  in  a  funnel  to 
drain  off  the  excess  of  mercury. 

Battery  Solution. 

For  a  Bunsen  element.  For  the  porous  cell  use  a  sat- 
urated solution  of  K2Cr2O7  to  which  has  been  added  one- 
fifth  its  volume  of  H8SO4.  For  the  outer  cell  use  a  solu- 
tion of  1  part  H2S04.  For  the  outer  cell  use  a  solution 
of  1  part  H2S04  and  nine  parts  water. 


i-  -sc: 

i -if- 


16Mar'53RL 


DEC  9     1954  LO 

IBW56RE 
J956 


REC'D 

JUL  26  1957 

21-100«-7,-52(A2528si6)476 


below. 


